diff --git a/src/main/kotlin/com/example/onui/domain/auth/presentation/AuthController.kt b/src/main/kotlin/com/example/onui/domain/auth/presentation/AuthController.kt
index f6e2613..2a44a41 100644
--- a/src/main/kotlin/com/example/onui/domain/auth/presentation/AuthController.kt
+++ b/src/main/kotlin/com/example/onui/domain/auth/presentation/AuthController.kt
@@ -4,6 +4,7 @@ import com.example.onui.domain.auth.presentation.dto.response.TokenResponse
 import com.example.onui.domain.auth.service.AppleAuthService
 import com.example.onui.domain.auth.service.AuthService
 import com.example.onui.domain.auth.service.GoogleAuthService
+import org.springframework.http.HttpStatus
 import org.springframework.validation.annotation.Validated
 import org.springframework.web.bind.annotation.*
 
@@ -17,6 +18,7 @@ class AuthController(
 ) {
 
     @PostMapping("/google")
+    @ResponseStatus(HttpStatus.CREATED)
     fun oauthSignIn(
         @RequestParam(name = "token", required = true)
         token: String
@@ -29,6 +31,7 @@ class AuthController(
     ): TokenResponse = authService.reissue(token)
 
     @PostMapping("/apple")
+    @ResponseStatus(HttpStatus.CREATED)
     fun oauthSignInWithApple(
         @RequestParam(name = "token", required = true)
         token: String
diff --git a/src/main/kotlin/com/example/onui/domain/auth/service/GoogleAuthServiceImpl.kt b/src/main/kotlin/com/example/onui/domain/auth/service/GoogleAuthServiceImpl.kt
index d5e2992..f932f96 100644
--- a/src/main/kotlin/com/example/onui/domain/auth/service/GoogleAuthServiceImpl.kt
+++ b/src/main/kotlin/com/example/onui/domain/auth/service/GoogleAuthServiceImpl.kt
@@ -4,6 +4,7 @@ import com.example.onui.domain.auth.presentation.dto.response.TokenResponse
 import com.example.onui.domain.auth.repository.RefreshTokenRepository
 import com.example.onui.domain.user.entity.User
 import com.example.onui.domain.user.repository.UserRepository
+import com.example.onui.global.config.error.exception.InvalidTokenException
 import com.example.onui.global.config.jwt.TokenProvider
 import com.example.onui.infra.feign.google.GoogleAuthClient
 import com.example.onui.infra.feign.google.GoogleInfoClient
@@ -31,12 +32,17 @@ class GoogleAuthServiceImpl(
 
         logger.info { token }
 
-        val response = googleInfo.googleInfo(ALT, token)
+        val response = try {
+            googleInfo.googleInfo(ALT, token)
+        } catch (e: Exception) {
+            throw InvalidTokenException
+        }
 
         refreshTokenRepository.findBySub(response.sub)?.let {
             refreshTokenRepository.delete(it)
         }
 
+        googleAuth.revokeToken(token)
         val tokenResponse = tokenProvider.receiveToken(response.sub)
 
         userRepository.findBySub(response.sub)
@@ -47,8 +53,6 @@ class GoogleAuthServiceImpl(
                 )
             )
 
-        googleAuth.revokeToken(token)
-
         return tokenResponse
     }
 }
\ No newline at end of file
diff --git a/src/main/kotlin/com/example/onui/domain/diary/entity/Diary.kt b/src/main/kotlin/com/example/onui/domain/diary/entity/Diary.kt
index f2ee99a..dd425da 100644
--- a/src/main/kotlin/com/example/onui/domain/diary/entity/Diary.kt
+++ b/src/main/kotlin/com/example/onui/domain/diary/entity/Diary.kt
@@ -2,6 +2,8 @@
 
 import com.example.onui.domain.diary.presentation.response.DiaryDetailResponse
 import com.example.onui.domain.diary.presentation.response.DiaryResponse
+import com.example.onui.domain.timeline.entity.Comment
+import com.example.onui.domain.timeline.presentation.dto.response.TimelineResponse
 import com.example.onui.domain.user.entity.User
 import com.example.onui.global.common.entity.BaseTimeEntity
 import java.time.LocalDateTime
@@ -54,6 +56,9 @@ Diary(
     var isPosted: Boolean = isPosted
         protected set
 
+    @OneToMany(mappedBy = "timeline", cascade = [CascadeType.REMOVE])
+    var commentList: MutableList<Comment> = arrayListOf()
+
     fun toResponse() = DiaryResponse(
         this.id!!,
         this.mood,
@@ -68,4 +73,14 @@ Diary(
         this.createdAt.toLocalDate(),
         this.image
     )
+
+    fun toTimelineResponse() = TimelineResponse(
+        this.id!!,
+        this.content,
+        this.mood,
+        this.tagList,
+        this.image,
+        this.user.name,
+        this.commentList.size
+    )
 }
\ No newline at end of file
diff --git a/src/main/kotlin/com/example/onui/domain/diary/repository/DiaryRepository.kt b/src/main/kotlin/com/example/onui/domain/diary/repository/DiaryRepository.kt
index 45bedc4..66d2dcb 100644
--- a/src/main/kotlin/com/example/onui/domain/diary/repository/DiaryRepository.kt
+++ b/src/main/kotlin/com/example/onui/domain/diary/repository/DiaryRepository.kt
@@ -14,4 +14,6 @@ interface DiaryRepository : JpaRepository<Diary, UUID?> {
     fun findByUserAndYearAndMonthAndDay(user: User, year: Int, month: Int, day: Int): Diary?
 
     fun existsByIdAndIsPosted(id: UUID, isPosted: Boolean): Boolean
+
+    fun findByIdAndIsPosted(id: UUID, isPosted: Boolean): Diary?
 }
\ No newline at end of file
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/entity/Comment.kt b/src/main/kotlin/com/example/onui/domain/timeline/entity/Comment.kt
new file mode 100644
index 0000000..b7c0de7
--- /dev/null
+++ b/src/main/kotlin/com/example/onui/domain/timeline/entity/Comment.kt
@@ -0,0 +1,47 @@
+package com.example.onui.domain.timeline.entity
+
+import com.example.onui.domain.diary.entity.Diary
+import com.example.onui.domain.timeline.presentation.dto.response.CommentResponse
+import com.example.onui.domain.user.entity.User
+import java.time.LocalDateTime
+import java.util.*
+import javax.persistence.*
+
+@Entity(name = "comment")
+class Comment(
+    content: String,
+    user: User,
+    timeline: Diary,
+    id: UUID? = null
+) {
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    @Column(columnDefinition = "BINARY(16)")
+    var id: UUID? = id
+        protected set
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "user_id", nullable = false)
+    var user: User = user
+        protected set
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "timeline_id", nullable = false)
+    var timeline: Diary = timeline
+        protected set
+
+    @Column(name = "content", columnDefinition = "VARCHAR(50)", nullable = false)
+    var content: String = content
+        protected set
+
+    @Column(name = "created_at", nullable = false)
+    var createdAt: LocalDateTime = LocalDateTime.now()
+        protected set
+
+    fun toResponse() = CommentResponse(
+        this.id!!,
+        this.timeline.id!!,
+        this.user.id!!,
+        this.content
+    )
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/exception/AlreadyPostedTimeLineException.kt b/src/main/kotlin/com/example/onui/domain/timeline/exception/AlreadyPostedTimelineException.kt
similarity index 77%
rename from src/main/kotlin/com/example/onui/domain/timeline/exception/AlreadyPostedTimeLineException.kt
rename to src/main/kotlin/com/example/onui/domain/timeline/exception/AlreadyPostedTimelineException.kt
index bc3b5b7..331feb7 100644
--- a/src/main/kotlin/com/example/onui/domain/timeline/exception/AlreadyPostedTimeLineException.kt
+++ b/src/main/kotlin/com/example/onui/domain/timeline/exception/AlreadyPostedTimelineException.kt
@@ -3,4 +3,4 @@
 import com.example.onui.global.config.error.data.ErrorCode
 import com.example.onui.global.config.error.exception.BusinessException
 
-object AlreadyPostedTimeLineException : BusinessException(ErrorCode.ALREADY_POSTED_TIMELINE)
+object AlreadyPostedTimelineException : BusinessException(ErrorCode.ALREADY_POSTED_TIMELINE)
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/exception/TimelineNotFoundException.kt b/src/main/kotlin/com/example/onui/domain/timeline/exception/TimelineNotFoundException.kt
new file mode 100644
index 0000000..b5808f2
--- /dev/null
+++ b/src/main/kotlin/com/example/onui/domain/timeline/exception/TimelineNotFoundException.kt
@@ -0,0 +1,6 @@
+package com.example.onui.domain.timeline.exception
+
+import com.example.onui.global.config.error.data.ErrorCode
+import com.example.onui.global.config.error.exception.BusinessException
+
+object TimelineNotFoundException : BusinessException(ErrorCode.TIMELINE_NOT_FOUND)
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/presentation/CommentController.kt b/src/main/kotlin/com/example/onui/domain/timeline/presentation/CommentController.kt
new file mode 100644
index 0000000..57973e9
--- /dev/null
+++ b/src/main/kotlin/com/example/onui/domain/timeline/presentation/CommentController.kt
@@ -0,0 +1,32 @@
+package com.example.onui.domain.timeline.presentation
+
+import com.example.onui.domain.timeline.presentation.dto.request.CommentRequest
+import com.example.onui.domain.timeline.service.TimelineService
+import org.springframework.http.HttpStatus
+import org.springframework.validation.annotation.Validated
+import org.springframework.web.bind.annotation.*
+import java.util.*
+import javax.validation.Valid
+
+@Validated
+@RestController
+@RequestMapping("/comment")
+class CommentController(
+    private val timelineService: TimelineService
+) {
+
+    @PostMapping
+    @ResponseStatus(HttpStatus.CREATED)
+    fun createComment(
+        @RequestParam("timeline_id", required = true)
+        timelineId: UUID,
+        @RequestBody @Valid
+        req: CommentRequest
+    ) = timelineService.comment(timelineId, req.comment)
+
+    @GetMapping
+    fun getComment(
+        @RequestParam("timeline_id", required = true)
+        timelineId: UUID
+    ) = timelineService.getComment(timelineId)
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/presentation/TimelineController.kt b/src/main/kotlin/com/example/onui/domain/timeline/presentation/TimelineController.kt
index 33ab5e8..2613ea0 100644
--- a/src/main/kotlin/com/example/onui/domain/timeline/presentation/TimelineController.kt
+++ b/src/main/kotlin/com/example/onui/domain/timeline/presentation/TimelineController.kt
@@ -1,7 +1,7 @@
 package com.example.onui.domain.timeline.presentation
 
 import com.example.onui.domain.timeline.exception.InvalidDateFormatException
-import com.example.onui.domain.timeline.service.TimeLineService
+import com.example.onui.domain.timeline.service.TimelineService
 import org.springframework.http.HttpStatus
 import org.springframework.validation.annotation.Validated
 import org.springframework.web.bind.annotation.*
@@ -13,14 +13,12 @@ import java.util.*
 @RestController
 @RequestMapping("/tl")
 class TimelineController(
-    private val timelineService: TimeLineService
+    private val timelineService: TimelineService
 ) {
 
     @PostMapping
     @ResponseStatus(HttpStatus.CREATED)
-    fun createTimeline(
-        @RequestParam("id", required = true) id: UUID
-    ) = timelineService.post(id)
+    fun createTimeline(@RequestParam("id", required = true) id: UUID) = timelineService.post(id)
 
     @GetMapping
     fun getByDate(
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/request/CommentRequest.kt b/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/request/CommentRequest.kt
new file mode 100644
index 0000000..c5ccbf7
--- /dev/null
+++ b/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/request/CommentRequest.kt
@@ -0,0 +1,11 @@
+package com.example.onui.domain.timeline.presentation.dto.request
+
+import javax.validation.constraints.NotBlank
+import javax.validation.constraints.Size
+
+data class CommentRequest(
+
+    @field:NotBlank(message = "comment는 null일 수 없습니다.")
+    @field:Size(max = 50, message = "댓글은 최대 50자 입니다.")
+    val comment: String
+)
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/response/CommentListResponse.kt b/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/response/CommentListResponse.kt
new file mode 100644
index 0000000..06725fe
--- /dev/null
+++ b/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/response/CommentListResponse.kt
@@ -0,0 +1,5 @@
+package com.example.onui.domain.timeline.presentation.dto.response
+
+data class CommentListResponse(
+    val commentList: MutableList<CommentResponse>?
+)
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/response/CommentResponse.kt b/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/response/CommentResponse.kt
new file mode 100644
index 0000000..210d128
--- /dev/null
+++ b/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/response/CommentResponse.kt
@@ -0,0 +1,10 @@
+package com.example.onui.domain.timeline.presentation.dto.response
+
+import java.util.*
+
+data class CommentResponse(
+    val id: UUID,
+    val timeline: UUID,
+    val user: UUID,
+    val content: String
+)
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/response/TimelineResponse.kt b/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/response/TimelineResponse.kt
index 21a61be..0f93e6c 100644
--- a/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/response/TimelineResponse.kt
+++ b/src/main/kotlin/com/example/onui/domain/timeline/presentation/dto/response/TimelineResponse.kt
@@ -1,17 +1,14 @@
 package com.example.onui.domain.timeline.presentation.dto.response
 
 import com.example.onui.domain.diary.entity.Mood
-import java.time.DayOfWeek
-import java.time.LocalDateTime
 import java.util.*
 
 data class TimelineResponse(
     val id: UUID,
     val content: String?,
     val mood: Mood,
-    val tag: MutableList<String>,
+    val tagList: MutableList<String>,
     val image: String?,
-    val dayOfWeek: DayOfWeek,
-    val createdAt: LocalDateTime,
-    val isUpdated: Boolean
-)
\ No newline at end of file
+    val writer: String,
+    val commentCount: Int
+)
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/repository/CommentRepository.kt b/src/main/kotlin/com/example/onui/domain/timeline/repository/CommentRepository.kt
new file mode 100644
index 0000000..adafc20
--- /dev/null
+++ b/src/main/kotlin/com/example/onui/domain/timeline/repository/CommentRepository.kt
@@ -0,0 +1,13 @@
+package com.example.onui.domain.timeline.repository
+
+import com.example.onui.domain.diary.entity.Diary
+import com.example.onui.domain.timeline.entity.Comment
+import org.springframework.data.jpa.repository.JpaRepository
+import org.springframework.stereotype.Repository
+import java.util.*
+
+@Repository
+interface CommentRepository : JpaRepository<Comment, UUID?> {
+
+    fun findAllByTimelineOrderByCreatedAtAsc(timeline: Diary): MutableList<Comment>
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/repository/QTimelineRepository.kt b/src/main/kotlin/com/example/onui/domain/timeline/repository/QTimelineRepository.kt
index 452a3b3..a6e45b0 100644
--- a/src/main/kotlin/com/example/onui/domain/timeline/repository/QTimelineRepository.kt
+++ b/src/main/kotlin/com/example/onui/domain/timeline/repository/QTimelineRepository.kt
@@ -1,11 +1,11 @@
 package com.example.onui.domain.timeline.repository
 
-import com.example.onui.domain.diary.presentation.response.DiaryDetailResponse
+import com.example.onui.domain.timeline.presentation.dto.response.TimelineResponse
 import org.springframework.data.domain.Page
 import org.springframework.data.domain.Pageable
 import java.time.LocalDate
 
 interface QTimelineRepository {
 
-    fun findPageByDate(pageable: Pageable, date: LocalDate): Page<DiaryDetailResponse>
+    fun findPageByDate(pageable: Pageable, date: LocalDate): Page<TimelineResponse>
 }
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/repository/QTimelineRepositoryImpl.kt b/src/main/kotlin/com/example/onui/domain/timeline/repository/QTimelineRepositoryImpl.kt
index e9214bc..6682381 100644
--- a/src/main/kotlin/com/example/onui/domain/timeline/repository/QTimelineRepositoryImpl.kt
+++ b/src/main/kotlin/com/example/onui/domain/timeline/repository/QTimelineRepositoryImpl.kt
@@ -1,7 +1,7 @@
 package com.example.onui.domain.timeline.repository
 
 import com.example.onui.domain.diary.entity.QDiary.diary
-import com.example.onui.domain.diary.presentation.response.DiaryDetailResponse
+import com.example.onui.domain.timeline.presentation.dto.response.TimelineResponse
 import com.querydsl.jpa.impl.JPAQueryFactory
 import org.springframework.data.domain.Page
 import org.springframework.data.domain.PageImpl
@@ -14,7 +14,7 @@ class QTimelineRepositoryImpl(
     private val query: JPAQueryFactory
 ) : QTimelineRepository {
 
-    override fun findPageByDate(pageable: Pageable, date: LocalDate): Page<DiaryDetailResponse> {
+    override fun findPageByDate(pageable: Pageable, date: LocalDate): Page<TimelineResponse> {
         val query = query.selectFrom(diary).where(
             diary.isPosted.eq(true).and(
                 diary.day.eq(date.dayOfMonth).and(
@@ -25,7 +25,7 @@ class QTimelineRepositoryImpl(
             )
         ).orderBy(diary.createdAt.desc()).offset(pageable.offset).limit(pageable.pageSize.toLong())
 
-        val iterable = query.fetch().map { it.toDetailResponse() }
+        val iterable = query.fetch().map { it.toTimelineResponse() }
 
         return PageImpl(iterable, pageable, iterable.size.toLong())
     }
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/service/TimeLineService.kt b/src/main/kotlin/com/example/onui/domain/timeline/service/TimeLineService.kt
deleted file mode 100644
index 8556d52..0000000
--- a/src/main/kotlin/com/example/onui/domain/timeline/service/TimeLineService.kt
+++ /dev/null
@@ -1,13 +0,0 @@
-package com.example.onui.domain.timeline.service
-
-import com.example.onui.domain.diary.presentation.response.DiaryDetailResponse
-import org.springframework.data.domain.Page
-import java.time.LocalDate
-import java.util.*
-
-interface TimeLineService {
-
-    fun post(id: UUID): DiaryDetailResponse
-
-    fun searchByDate(idx: Int, size: Int, date: LocalDate): Page<DiaryDetailResponse>
-}
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/service/TimelineService.kt b/src/main/kotlin/com/example/onui/domain/timeline/service/TimelineService.kt
new file mode 100644
index 0000000..a8537f5
--- /dev/null
+++ b/src/main/kotlin/com/example/onui/domain/timeline/service/TimelineService.kt
@@ -0,0 +1,19 @@
+package com.example.onui.domain.timeline.service
+
+import com.example.onui.domain.timeline.presentation.dto.response.CommentListResponse
+import com.example.onui.domain.timeline.presentation.dto.response.CommentResponse
+import com.example.onui.domain.timeline.presentation.dto.response.TimelineResponse
+import org.springframework.data.domain.Page
+import java.time.LocalDate
+import java.util.*
+
+interface TimelineService {
+
+    fun post(id: UUID): TimelineResponse
+
+    fun searchByDate(idx: Int, size: Int, date: LocalDate): Page<TimelineResponse>
+
+    fun comment(timelineId: UUID, comment: String): CommentResponse
+
+    fun getComment(timelineId: UUID): CommentListResponse
+}
diff --git a/src/main/kotlin/com/example/onui/domain/timeline/service/TimelineServiceImpl.kt b/src/main/kotlin/com/example/onui/domain/timeline/service/TimelineServiceImpl.kt
index 7211091..def6f7b 100644
--- a/src/main/kotlin/com/example/onui/domain/timeline/service/TimelineServiceImpl.kt
+++ b/src/main/kotlin/com/example/onui/domain/timeline/service/TimelineServiceImpl.kt
@@ -2,9 +2,14 @@
 
 import com.example.onui.domain.diary.entity.Diary
 import com.example.onui.domain.diary.exception.DiaryNotFoundException
-import com.example.onui.domain.diary.presentation.response.DiaryDetailResponse
 import com.example.onui.domain.diary.repository.DiaryRepository
-import com.example.onui.domain.timeline.exception.AlreadyPostedTimeLineException
+import com.example.onui.domain.timeline.entity.Comment
+import com.example.onui.domain.timeline.exception.AlreadyPostedTimelineException
+import com.example.onui.domain.timeline.exception.TimelineNotFoundException
+import com.example.onui.domain.timeline.presentation.dto.response.CommentListResponse
+import com.example.onui.domain.timeline.presentation.dto.response.CommentResponse
+import com.example.onui.domain.timeline.presentation.dto.response.TimelineResponse
+import com.example.onui.domain.timeline.repository.CommentRepository
 import com.example.onui.domain.timeline.repository.QTimelineRepository
 import com.example.onui.global.common.facade.UserFacade
 import com.example.onui.global.config.error.exception.PermissionDeniedException
@@ -21,36 +26,52 @@ import java.util.*
 class TimelineServiceImpl(
     private val userFacade: UserFacade,
     private val qTimelineRepository: QTimelineRepository,
-    private val diaryRepository: DiaryRepository
-) : TimeLineService {
+    private val diaryRepository: DiaryRepository,
+    private val commentRepository: CommentRepository
+) : TimelineService {
 
     @Transactional
-    override fun post(id: UUID): DiaryDetailResponse {
+    override fun post(id: UUID): TimelineResponse {
         val user = userFacade.getCurrentUser()
 
-        val diary = diaryRepository.findByIdOrNull(id)
-            ?: throw DiaryNotFoundException
+        val diary = diaryRepository.findByIdOrNull(id) ?: throw DiaryNotFoundException
 
         if (diary.user != user) throw PermissionDeniedException
 
-        if (diaryRepository.existsByIdAndIsPosted(id, true)) throw AlreadyPostedTimeLineException
+        if (diaryRepository.existsByIdAndIsPosted(id, true)) throw AlreadyPostedTimelineException
 
         return diaryRepository.save(
             Diary(
-                diary.user,
-                diary.content,
-                diary.mood,
-                diary.tagList,
-                diary.createdAt,
-                diary.image,
-                diary.id,
-                true
+                diary.user, diary.content, diary.mood, diary.tagList, diary.createdAt, diary.image, diary.id, true
             )
-        ).toDetailResponse()
+        ).toTimelineResponse()
     }
 
-    override fun searchByDate(idx: Int, size: Int, date: LocalDate) = qTimelineRepository
-        .findPageByDate(
-            PageRequest.of(idx, size, Sort.by("diary.createdAt").descending()), date
-        )
+    override fun searchByDate(idx: Int, size: Int, date: LocalDate) = qTimelineRepository.findPageByDate(
+        PageRequest.of(idx, size, Sort.by("diary.createdAt").descending()), date
+    )
+
+    @Transactional
+    override fun comment(timelineId: UUID, comment: String): CommentResponse {
+
+        val timeline = diaryRepository.findByIdAndIsPosted(timelineId, true) ?: throw TimelineNotFoundException
+
+        return commentRepository.save(
+            Comment(
+                comment, userFacade.getCurrentUser(), timeline
+            )
+        ).toResponse()
+    }
+
+    override fun getComment(timelineId: UUID): CommentListResponse {
+
+        val timeline = diaryRepository.findByIdAndIsPosted(timelineId, true) ?: throw TimelineNotFoundException
+
+        val commentList =
+            commentRepository.findAllByTimelineOrderByCreatedAtAsc(timeline).map { it.toResponse() }.toMutableList()
+
+        return CommentListResponse(if (commentList.isEmpty()) null else commentList)
+    }
+
+
 }
\ No newline at end of file
diff --git a/src/main/kotlin/com/example/onui/domain/user/entity/User.kt b/src/main/kotlin/com/example/onui/domain/user/entity/User.kt
index 1c5db18..c977d46 100644
--- a/src/main/kotlin/com/example/onui/domain/user/entity/User.kt
+++ b/src/main/kotlin/com/example/onui/domain/user/entity/User.kt
@@ -1,6 +1,7 @@
 package com.example.onui.domain.user.entity
 
 import com.example.onui.domain.diary.entity.Diary
+import com.example.onui.domain.timeline.entity.Comment
 import com.example.onui.domain.user.presentation.dto.response.UserProfileResponse
 import org.hibernate.annotations.DynamicUpdate
 import java.util.*
@@ -31,6 +32,9 @@ class User(
     @OneToMany(mappedBy = "user", cascade = [CascadeType.REMOVE])
     var diaryList: MutableList<Diary> = arrayListOf()
 
+    @OneToMany(mappedBy = "user", cascade = [CascadeType.REMOVE])
+    var commentList: MutableList<Comment> = arrayListOf()
+
     fun toResponse() = UserProfileResponse(
         this.sub,
         this.name
diff --git a/src/main/kotlin/com/example/onui/global/config/error/data/ErrorCode.kt b/src/main/kotlin/com/example/onui/global/config/error/data/ErrorCode.kt
index 82a7c50..b4100ad 100644
--- a/src/main/kotlin/com/example/onui/global/config/error/data/ErrorCode.kt
+++ b/src/main/kotlin/com/example/onui/global/config/error/data/ErrorCode.kt
@@ -23,6 +23,7 @@ enum class ErrorCode(
 
     // 404
     DIARY_NOT_FOUND(HttpStatus.NOT_FOUND, "감정 기록을 찾을 수 없습니다."),
+    TIMELINE_NOT_FOUND(HttpStatus.NOT_FOUND, "타임라인을 찾을 수 없습니다."),
 
     // 500
     INTERNAL_SERVER_ERROR(HttpStatus.INTERNAL_SERVER_ERROR, "서버 내부 에러")