diff --git a/src/main/java/space/space_spring/response/status/BaseExceptionResponseStatus.java b/src/main/java/space/space_spring/response/status/BaseExceptionResponseStatus.java
index a6af3f78..64174408 100644
--- a/src/main/java/space/space_spring/response/status/BaseExceptionResponseStatus.java
+++ b/src/main/java/space/space_spring/response/status/BaseExceptionResponseStatus.java
@@ -109,7 +109,9 @@ public enum BaseExceptionResponseStatus implements ResponseStatus {
     NOT_LIKED_THE_POST_YET(11003, HttpStatus.BAD_REQUEST, "유저가 해당 게시글에 좋아요를 누르지 않았습니다."),
     COMMENT_NOT_EXIST(11004, HttpStatus.NOT_FOUND, "존재하지 않는 댓글 id입니다."),
     ALREADY_LIKED_THE_COMMENT(11005, HttpStatus.BAD_REQUEST, "해당 댓글에 이미 좋아요를 눌렀습니다."),
-    NOT_LIKED_THE_COMMENT_YET(11006, HttpStatus.BAD_REQUEST, "유저가 해당 댓글에 좋아요를 누르지 않았습니다.");
+    NOT_LIKED_THE_COMMENT_YET(11006, HttpStatus.BAD_REQUEST, "유저가 해당 댓글에 좋아요를 누르지 않았습니다."),
+    INVALID_REPLY_TARGET(11007, HttpStatus.BAD_REQUEST, "대댓글 일 때는 targetId는 null 일 수 없습니다."),
+    INVALID_COMMENT_TARGET(11008, HttpStatus.BAD_REQUEST, "댓글일 때는 targetId가 null이어야 합니다.");
 
     private final int code;
     private final HttpStatus status;
diff --git a/src/main/java/space/space_spring/service/CommentService.java b/src/main/java/space/space_spring/service/CommentService.java
index 2f28fefa..7b9a5071 100644
--- a/src/main/java/space/space_spring/service/CommentService.java
+++ b/src/main/java/space/space_spring/service/CommentService.java
@@ -32,7 +32,6 @@ public class CommentService {
     private final UserSpaceDao userSpaceDao;
     private final UserUtils userUtils;
     private final UserSpaceUtils userSpaceUtils;
-    private final LikeService likeService;
 
     // TODO 1: 유저가 스페이스에 속하는지 검증
     public void validateUserInSpace(Long userId, Long spaceId) {
@@ -64,6 +63,14 @@ public List<ReadCommentsResponse> getCommentsByPost(Long postId, Long userId) {
 
     @Transactional
     public Long createComment(Long userId, Long postId, CreateCommentRequest.Request createCommentRequest) {
+        // TODO 1: isReply와 targetId 유효성 검사
+        if(createCommentRequest.isReply() && createCommentRequest.getTargetId() == null) {
+            throw new CustomException(INVALID_REPLY_TARGET);
+        }
+        if(!createCommentRequest.isReply() && createCommentRequest.getTargetId() != null) {
+            throw new CustomException(INVALID_COMMENT_TARGET);
+        }
+
         // TODO 1: userId에 해당하는 user find
         User user = userUtils.findUserByUserId(userId);
 
@@ -71,6 +78,7 @@ public Long createComment(Long userId, Long postId, CreateCommentRequest.Request
         Post post = postDao.findById(postId)
                 .orElseThrow(() -> new CustomException(POST_NOT_EXIST));
 
+        // TODO 3: 댓글 또는 대댓글 생성
         Comment comment = createCommentRequest.toEntity(user, post);
         commentDao.save(comment);