diff --git a/src/main/java/com/back/domain/post/post/entity/Post.java b/src/main/java/com/back/domain/post/post/entity/Post.java
index 7079188..f103796 100644
--- a/src/main/java/com/back/domain/post/post/entity/Post.java
+++ b/src/main/java/com/back/domain/post/post/entity/Post.java
@@ -115,6 +115,15 @@ public void updateContent(String content) {
     this.content = content;
   }
 
+  public void addImage(PostImage image) {
+    if (this.images == null) {
+      this.images = new ArrayList<>();
+    }
+    this.images.add(image);
+    image.updatePost(this); // 양방향 관계 유지
+  }
+
+
   public void updateImages(List<PostImage> images) {
     this.images.clear();
     for (PostImage i : images) {
diff --git a/src/main/java/com/back/domain/post/post/service/PostService.java b/src/main/java/com/back/domain/post/post/service/PostService.java
index 6ae3218..603016f 100644
--- a/src/main/java/com/back/domain/post/post/service/PostService.java
+++ b/src/main/java/com/back/domain/post/post/service/PostService.java
@@ -79,13 +79,12 @@ public PostResponseDto createPost(PostCreateRequestDto reqBody, List<MultipartFi
         String url = fileService.uploadFile(image);
 
         PostImage postImage = PostImage.builder()
-            .post(post)
             .fileName(image.getOriginalFilename())
             .url(url)
             .sortOrder(order++)
             .build();
 
-        postImageRepository.save(postImage);
+        post.addImage(postImage);
       }
     }