diff --git a/go.mod b/go.mod
index d65e4217..0dc8cc3d 100644
--- a/go.mod
+++ b/go.mod
@@ -4,7 +4,6 @@ go 1.20
 
 require (
 	github.com/arran4/golang-ical v0.1.0
-	github.com/carlescere/scheduler v0.0.0-20170109141437-ee74d2f83d82
 	github.com/go-gormigrate/gormigrate/v2 v2.1.1
 	github.com/go-sql-driver/mysql v1.7.1
 	github.com/gofrs/uuid v4.4.0+incompatible
@@ -16,6 +15,7 @@ require (
 	github.com/labstack/echo/v4 v4.11.1
 	github.com/ory/dockertest/v3 v3.10.0
 	github.com/patrickmn/go-cache v2.1.0+incompatible
+	github.com/robfig/cron/v3 v3.0.1
 	github.com/stretchr/testify v1.8.4
 	github.com/traPtitech/go-traq v0.0.0-20220822084224-d405d26bce99
 	go.uber.org/zap v1.26.0
diff --git a/go.sum b/go.sum
index 95ad4ac3..1e05b885 100644
--- a/go.sum
+++ b/go.sum
@@ -13,8 +13,6 @@ github.com/Nvveen/Gotty v0.0.0-20120604004816-cd527374f1e5 h1:TngWCqHvy9oXAN6lEV
 github.com/Nvveen/Gotty v0.0.0-20120604004816-cd527374f1e5/go.mod h1:lmUJ/7eu/Q8D7ML55dXQrVaamCz2vxCfdQBasLZfHKk=
 github.com/arran4/golang-ical v0.1.0 h1:Oz0Rd5fpeNoHNFF9B9H5uYZyt1ubuZSZ3LVdHD5KvZI=
 github.com/arran4/golang-ical v0.1.0/go.mod h1:BSTTrYHuM12oAL8jDdcmPdw02SBThKYWNFHQlvEG6b0=
-github.com/carlescere/scheduler v0.0.0-20170109141437-ee74d2f83d82 h1:9bAydALqAjBfPHd/eAiJBHnMZUYov8m2PkXVr+YGQeI=
-github.com/carlescere/scheduler v0.0.0-20170109141437-ee74d2f83d82/go.mod h1:tyA14J0sA3Hph4dt+AfCjPrYR13+vVodshQSM7km9qw=
 github.com/cenkalti/backoff/v4 v4.1.3 h1:cFAlzYUlVYDysBEH2T5hyJZMh3+5+WCBvSnK6Q8UtC4=
 github.com/cenkalti/backoff/v4 v4.1.3/go.mod h1:scbssz8iZGpm3xbr14ovlUdkxfGXNInqkPWOWmG2CLw=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
@@ -160,6 +158,8 @@ github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINE
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
+github.com/robfig/cron/v3 v3.0.1 h1:WdRxkvbJztn8LMz/QEvLN5sBU+xKpSqwwUO1Pjr4qDs=
+github.com/robfig/cron/v3 v3.0.1/go.mod h1:eQICP3HwyT7UooqI/z+Ov+PtYAWygg1TEWWzGIFLtro=
 github.com/rogpeppe/go-internal v1.11.0 h1:cWPaGQEPrBb5/AsnsZesgZZ9yb1OQ+GOISoDNXVBh4M=
 github.com/rogpeppe/go-internal v1.11.0/go.mod h1:ddIwULY96R17DhadqLgMfk9H9tvdUzkipdSkR5nkCZA=
 github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
diff --git a/main.go b/main.go
index 5adc4829..6aada222 100644
--- a/main.go
+++ b/main.go
@@ -10,15 +10,16 @@ import (
 
 	"github.com/traPtitech/knoQ/domain"
 	"github.com/traPtitech/knoQ/infra/db"
-	"github.com/traPtitech/knoQ/repository"
 	"github.com/traPtitech/knoQ/infra/traq"
+	"github.com/traPtitech/knoQ/repository"
 	"github.com/traPtitech/knoQ/utils"
+	"github.com/traPtitech/knoQ/utils/tz"
 	"golang.org/x/oauth2"
 
 	"github.com/traPtitech/knoQ/router"
 
-	"github.com/carlescere/scheduler"
 	"github.com/gorilla/sessions"
+	"github.com/robfig/cron/v3"
 	"go.uber.org/zap"
 )
 
@@ -42,8 +43,6 @@ var (
 	webhookSecret     = getenv("WEBHOOK_SECRET", "")
 	activityChannelID = getenv("ACTIVITY_CHANNEL_ID", "")
 	dailyChannelID    = getenv("DAILY_CHANNEL_ID", "")
-
-	jst, _ = time.LoadLocation("Asia/Tokyo")
 )
 
 func main() {
@@ -53,7 +52,7 @@ func main() {
 	domain.DEVELOPMENT, _ = strconv.ParseBool(development)
 
 	gormRepo := db.GormRepository{}
-	err := gormRepo.Setup(mariadbHost, mariadbUser, mariadbPassword, mariadbDatabase, mariadbPort, tokenKey, gormLogLevel, jst)
+	err := gormRepo.Setup(mariadbHost, mariadbUser, mariadbPassword, mariadbDatabase, mariadbPort, tokenKey, gormLogLevel, tz.JST)
 	if err != nil {
 		panic(err)
 	}
@@ -94,9 +93,21 @@ func main() {
 	e := handler.SetupRoute()
 
 	// webhook
-	job := utils.InitPostEventToTraQ(&repo.GormRepo, handler.WebhookSecret,
-		handler.DailyChannelId, handler.WebhookID, handler.Origin)
-	_, _ = scheduler.Every().Day().At("08:00").Run(job)
+	c := cron.New(cron.WithLocation(tz.JST))
+	_, err = c.AddFunc(
+		"0 8 * * *",
+		utils.InitPostEventToTraQ(
+			&repo.GormRepo,
+			handler.WebhookSecret,
+			handler.DailyChannelId,
+			handler.WebhookID,
+			handler.Origin,
+		),
+	)
+	if err != nil {
+		panic(err)
+	}
+	c.Start()
 
 	// サーバースタート
 	go func() {
diff --git a/router/presentation/event.go b/router/presentation/event.go
index 0de5e2f2..c9af7130 100644
--- a/router/presentation/event.go
+++ b/router/presentation/event.go
@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/traPtitech/knoQ/domain"
+	"github.com/traPtitech/knoQ/utils/tz"
 
 	ics "github.com/arran4/golang-ical"
 	"github.com/gofrs/uuid"
@@ -161,7 +162,6 @@ func ICalFormat(events []*domain.Event, host string, userMap map[uuid.UUID]*doma
 }
 
 func GenerateEventWebhookContent(method string, e *EventDetailRes, nofiticationTargets []string, origin string, isMention bool) string {
-	jst, _ := time.LoadLocation("Asia/Tokyo")
 	timeFormat := "01/02(Mon) 15:04"
 	var content string
 	switch method {
@@ -172,7 +172,7 @@ func GenerateEventWebhookContent(method string, e *EventDetailRes, nofiticationT
 	}
 	content += fmt.Sprintf("### [%s](%s/events/%s)", e.Name, origin, e.ID) + "\n"
 	content += fmt.Sprintf("- 主催: [%s](%s/groups/%s)", e.GroupName, origin, e.Group.ID) + "\n"
-	content += fmt.Sprintf("- 日時: %s ~ %s", e.TimeStart.In(jst).Format(timeFormat), e.TimeEnd.In(jst).Format(timeFormat)) + "\n"
+	content += fmt.Sprintf("- 日時: %s ~ %s", e.TimeStart.In(tz.JST).Format(timeFormat), e.TimeEnd.In(tz.JST).Format(timeFormat)) + "\n"
 	content += fmt.Sprintf("- 場所: %s", e.Room.Place) + "\n"
 	content += "\n"
 
diff --git a/router/presentation/room.go b/router/presentation/room.go
index cca48be6..b9406597 100644
--- a/router/presentation/room.go
+++ b/router/presentation/room.go
@@ -5,6 +5,7 @@ import (
 
 	"github.com/gofrs/uuid"
 	"github.com/traPtitech/knoQ/domain"
+	"github.com/traPtitech/knoQ/utils/tz"
 )
 
 //go:generate go run github.com/fuji8/gotypeconverter/cmd/gotypeconverter@latest -s RoomReq -d domain.WriteRoomParams -o converter.go .
@@ -75,17 +76,16 @@ func ConvdomainRoomToRoomRes(src domain.Room) (dst RoomRes) {
 func ChangeRoomCSVReqTodomainWriteRoomParams(src RoomCSVReq, userID uuid.UUID) (*domain.WriteRoomParams, error) {
 
 	layout := "2006/01/02 15:04"
-	jst, _ := time.LoadLocation("Asia/Tokyo")
 	var params domain.WriteRoomParams
 	var err error
 
 	params.Place = src.Location
-	params.TimeStart, err = time.ParseInLocation(layout, src.StartDate+" "+src.StartTime, jst)
+	params.TimeStart, err = time.ParseInLocation(layout, src.StartDate+" "+src.StartTime, tz.JST)
 	if err != nil {
 		return nil, err
 	}
 
-	params.TimeEnd, err = time.ParseInLocation(layout, src.EndDate+" "+src.EndTime, jst)
+	params.TimeEnd, err = time.ParseInLocation(layout, src.EndDate+" "+src.EndTime, tz.JST)
 	if err != nil {
 		return nil, err
 	}
diff --git a/utils/cron.go b/utils/cron.go
index 7edb6e52..9112c6a4 100644
--- a/utils/cron.go
+++ b/utils/cron.go
@@ -9,11 +9,10 @@ import (
 	"github.com/traPtitech/knoQ/domain"
 	"github.com/traPtitech/knoQ/domain/filter"
 	"github.com/traPtitech/knoQ/infra/db"
+	"github.com/traPtitech/knoQ/utils/tz"
 	"golang.org/x/exp/slices"
 )
 
-var jst, _ = time.LoadLocation("Asia/Tokyo")
-
 type timeTable struct {
 	name           string
 	start          time.Time
@@ -41,7 +40,7 @@ func InitPostEventToTraQ(repo *db.GormRepository, secret, channelID, webhookID,
 
 func setTimeFromString(t time.Time, str string) time.Time {
 	s, _ := time.Parse(time.TimeOnly, str)
-	return time.Date(t.Year(), t.Month(), t.Day(), s.Hour(), s.Minute(), s.Second(), 0, jst)
+	return time.Date(t.Year(), t.Month(), t.Day(), s.Hour(), s.Minute(), s.Second(), 0, tz.JST)
 }
 
 // makeRoomAvailableByTimeTable timeTables の各時間帯を行、rooms の各部屋を列とする表を map 形式で作成する。 unVerified の部屋は無視する。
@@ -97,7 +96,7 @@ func makeRoomAvailableByTimeTable(rooms []*domain.Room, timeTables []timeTable,
 }
 
 func createMessage(t time.Time, rooms []*domain.Room, events []*db.Event, origin string) string {
-	date := t.In(jst).Format("01/02(Mon)")
+	date := t.In(tz.JST).Format("01/02(Mon)")
 	combined := map[bool]string{
 		true:  "(併用可)",
 		false: "",
@@ -164,7 +163,7 @@ func createMessage(t time.Time, rooms []*domain.Room, events []*db.Event, origin
 	} else {
 		for _, event := range events {
 			eventMessage += fmt.Sprintf("- [%s](%s/events/%s) %s ~ %s @%s %s\n", event.Name, origin, event.ID,
-				event.TimeStart.In(jst).Format("15:04"), event.TimeEnd.In(jst).Format("15:04"),
+				event.TimeStart.In(tz.JST).Format("15:04"), event.TimeEnd.In(tz.JST).Format("15:04"),
 				event.Room.Place, combined[event.AllowTogether])
 		}
 
diff --git a/utils/format.go b/utils/format.go
deleted file mode 100644
index 0fbaa362..00000000
--- a/utils/format.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package utils
-
-import "time"
-
-func StrToTime(s string) (time.Time, error) {
-	t, err := time.Parse("15:04", s)
-	if err != nil {
-		t, err = time.Parse("15:04:05", s)
-		if err != nil {
-			return time.Time{}, err
-		}
-	}
-	return t, nil
-}
diff --git a/utils/tz/jst.go b/utils/tz/jst.go
new file mode 100644
index 00000000..d7a20430
--- /dev/null
+++ b/utils/tz/jst.go
@@ -0,0 +1,5 @@
+package tz
+
+import "time"
+
+var JST = time.FixedZone("Asia/Tokyo", 9*60*60)