diff --git a/src/main/kotlin/com/example/highthon/domain/auth/service/SmsServiceImpl.kt b/src/main/kotlin/com/example/highthon/domain/auth/service/SmsServiceImpl.kt
index 099066a..bd7fc9f 100644
--- a/src/main/kotlin/com/example/highthon/domain/auth/service/SmsServiceImpl.kt
+++ b/src/main/kotlin/com/example/highthon/domain/auth/service/SmsServiceImpl.kt
@@ -88,7 +88,7 @@ class SmsServiceImpl(
     @Transactional
     override fun sendPhoneNumberMessage(req: PhoneNumberSmsRequest): SingleMessageSentResponse? {
 
-        if (userRepository.existsByPhoneNumber(req.phoneNumber!!)) throw AlreadySignUpException
+        if (!userRepository.existsByPhoneNumber(req.phoneNumber!!)) throw PhoneNumberNotExistException
 
         if (qualificationRepository.existsById(req.phoneNumber)) throw AlreadyPostedMessageException