diff --git a/src/main/kotlin/co/bearus/magcloud/controller/DiaryCommentController.kt b/src/main/kotlin/co/bearus/magcloud/controller/DiaryCommentController.kt
index a0d3b4d..abcfe3a 100644
--- a/src/main/kotlin/co/bearus/magcloud/controller/DiaryCommentController.kt
+++ b/src/main/kotlin/co/bearus/magcloud/controller/DiaryCommentController.kt
@@ -8,12 +8,15 @@ import co.bearus.magcloud.controller.dto.request.DiaryCommentCreateDTO
 import co.bearus.magcloud.controller.dto.request.DiaryCommentDTO
 import co.bearus.magcloud.controller.dto.response.APIResponse
 import co.bearus.magcloud.domain.entity.diary.DiaryCommentEntity
+import co.bearus.magcloud.domain.exception.NotFriendException
 import co.bearus.magcloud.domain.repository.JPADiaryCommentRepository
 import co.bearus.magcloud.domain.repository.QUserDiaryRepository
 import co.bearus.magcloud.domain.service.diary.UserDiaryService
+import co.bearus.magcloud.domain.service.friend.FriendService
 import co.bearus.magcloud.domain.service.notification.NotificationService
 import co.bearus.magcloud.domain.type.ContextLanguage
 import co.bearus.magcloud.util.ULIDUtils
+import jakarta.validation.Valid
 import org.springframework.data.repository.findByIdOrNull
 import org.springframework.transaction.annotation.Transactional
 import org.springframework.web.bind.annotation.*
@@ -25,15 +28,19 @@ class DiaryCommentController(
     private val diaryService: UserDiaryService,
     private val qUserDiaryRepository: QUserDiaryRepository,
     private val notificationService: NotificationService,
+    private val friendService: FriendService,
 ) {
     @Transactional
     @PostMapping
     fun createComment(
         @RequestUser user: WebUser,
         @PathVariable diaryId: String,
-        @RequestBody body: DiaryCommentCreateDTO,
+        @RequestBody @Valid body: DiaryCommentCreateDTO,
     ): DiaryCommentDTO {
         val diary = diaryService.getDiaryById(diaryId)
+        if (diary.userId != user.userId && !friendService.isFriend(diary.userId, user.userId))
+            throw NotFriendException()
+
         val comment = DiaryCommentEntity.createNewComment(
             commentId = ULIDUtils.generate(),
             diaryId = diary.diaryId,
diff --git a/src/main/kotlin/co/bearus/magcloud/controller/dto/request/DiaryCreateDTO.kt b/src/main/kotlin/co/bearus/magcloud/controller/dto/request/DiaryCreateDTO.kt
index ea35a38..6b79615 100644
--- a/src/main/kotlin/co/bearus/magcloud/controller/dto/request/DiaryCreateDTO.kt
+++ b/src/main/kotlin/co/bearus/magcloud/controller/dto/request/DiaryCreateDTO.kt
@@ -12,7 +12,7 @@ data class DiaryCreateDTO(
 )
 
 data class DiaryCommentCreateDTO(
-    val content: String,
+    @field:NotEmpty(message = "내용은 비어있을 수 없습니다") val content: String,
 )
 
 data class DiaryCommentDTO(