diff --git a/backend/src/main/java/org/sejongisc/backend/board/dto/BoardResponse.java b/backend/src/main/java/org/sejongisc/backend/board/dto/BoardResponse.java
index b7a32c94..b96c7bb8 100644
--- a/backend/src/main/java/org/sejongisc/backend/board/dto/BoardResponse.java
+++ b/backend/src/main/java/org/sejongisc/backend/board/dto/BoardResponse.java
@@ -8,7 +8,7 @@
 import lombok.Setter;
 import lombok.ToString;
 import org.sejongisc.backend.board.entity.Board;
-import org.sejongisc.backend.user.entity.User;
+import org.sejongisc.backend.user.dto.UserInfoResponse;
 
 @ToString
 @AllArgsConstructor
@@ -22,15 +22,15 @@ public class BoardResponse {
 
   private String boardName;
 
-  private User createdBy;
+  private UserInfoResponse createdBy;
 
   private UUID parentBoardId;
 
-  public static BoardResponse of(Board board) {
+  public static BoardResponse from(Board board) {
     return BoardResponse.builder()
         .boardId(board.getBoardId())
         .boardName(board.getBoardName())
-        .createdBy(board.getCreatedBy())
+        .createdBy(UserInfoResponse.from(board.getCreatedBy()))
         .parentBoardId(board.getParentBoard() != null ? board.getParentBoard().getBoardId() : null)
         .build();
   }
diff --git a/backend/src/main/java/org/sejongisc/backend/board/dto/CommentResponse.java b/backend/src/main/java/org/sejongisc/backend/board/dto/CommentResponse.java
index 3e8f4092..eb2a7879 100644
--- a/backend/src/main/java/org/sejongisc/backend/board/dto/CommentResponse.java
+++ b/backend/src/main/java/org/sejongisc/backend/board/dto/CommentResponse.java
@@ -10,7 +10,7 @@
 import lombok.Setter;
 import lombok.ToString;
 import org.sejongisc.backend.board.entity.Comment;
-import org.sejongisc.backend.user.entity.User;
+import org.sejongisc.backend.user.dto.UserInfoResponse;
 
 @ToString
 @AllArgsConstructor
@@ -20,17 +20,17 @@
 @Builder
 public class CommentResponse {
     private UUID commentId;
-    private User user;
+    private UserInfoResponse user;
     private UUID postId;
     private String content;
     private LocalDateTime createdDate;
     private LocalDateTime updatedDate;
     private List<CommentResponse> replies;
 
-  public static CommentResponse of(Comment comment) {
+  public static CommentResponse from(Comment comment) {
     return CommentResponse.builder()
         .commentId(comment.getCommentId())
-        .user(comment.getUser())
+        .user(UserInfoResponse.from(comment.getUser()))
         .postId(comment.getPost().getPostId())
         .content(comment.getContent())
         .createdDate(comment.getCreatedDate())
@@ -38,10 +38,10 @@ public static CommentResponse of(Comment comment) {
         .build();
   }
 
-  public static CommentResponse of(Comment comment, List<CommentResponse> replies) {
+  public static CommentResponse from(Comment comment, List<CommentResponse> replies) {
     return CommentResponse.builder()
         .commentId(comment.getCommentId())
-        .user(comment.getUser())
+        .user(UserInfoResponse.from(comment.getUser()))
         .postId(comment.getPost().getPostId())
         .content(comment.getContent())
         .createdDate(comment.getCreatedDate())
diff --git a/backend/src/main/java/org/sejongisc/backend/board/dto/PostResponse.java b/backend/src/main/java/org/sejongisc/backend/board/dto/PostResponse.java
index 013b4d3e..780ce15c 100644
--- a/backend/src/main/java/org/sejongisc/backend/board/dto/PostResponse.java
+++ b/backend/src/main/java/org/sejongisc/backend/board/dto/PostResponse.java
@@ -9,8 +9,7 @@
 import lombok.NoArgsConstructor;
 import lombok.Setter;
 import lombok.ToString;
-import org.sejongisc.backend.board.entity.Board;
-import org.sejongisc.backend.user.entity.User;
+import org.sejongisc.backend.user.dto.UserInfoResponse;
 import org.springframework.data.domain.Page;
 
 @ToString
@@ -22,8 +21,8 @@
 public class PostResponse {
 
   private UUID postId;
-  private Board board;
-  private User user;
+  private BoardResponse board;
+  private UserInfoResponse user;
   private String title;
   private String content;
   private Integer bookmarkCount;
diff --git a/backend/src/main/java/org/sejongisc/backend/board/service/PostServiceImpl.java b/backend/src/main/java/org/sejongisc/backend/board/service/PostServiceImpl.java
index 5d00a363..a0818442 100644
--- a/backend/src/main/java/org/sejongisc/backend/board/service/PostServiceImpl.java
+++ b/backend/src/main/java/org/sejongisc/backend/board/service/PostServiceImpl.java
@@ -23,6 +23,7 @@
 import org.sejongisc.backend.common.exception.CustomException;
 import org.sejongisc.backend.common.exception.ErrorCode;
 import org.sejongisc.backend.user.dao.UserRepository;
+import org.sejongisc.backend.user.dto.UserInfoResponse;
 import org.sejongisc.backend.user.entity.User;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.PageRequest;
@@ -235,11 +236,11 @@ public PostResponse getPostDetail(UUID postId, int pageNumber, int pageSize) {
 
       // 자식 댓글 목록을 CommentResponse DTO 리스트로 변환
       List<CommentResponse> replyResponses = childComments.stream()
-          .map(CommentResponse::of)
+          .map(CommentResponse::from)
           .toList();
 
       // 부모 댓글 DTO를 생성하며, 자식 DTO 리스트를 주입
-      return CommentResponse.of(parent, replyResponses);
+      return CommentResponse.from(parent, replyResponses);
     });
 
     // 첨부 파일 조회
@@ -251,8 +252,8 @@ public PostResponse getPostDetail(UUID postId, int pageNumber, int pageSize) {
     // PostResponse DTO를 직접 빌드하여 반환
     return PostResponse.builder()
         .postId(post.getPostId())
-        .board(post.getBoard())
-        .user(post.getUser())
+        .board(BoardResponse.from(post.getBoard()))
+        .user(UserInfoResponse.from(post.getUser()))
         .title(post.getTitle())
         .content(post.getContent())
         .bookmarkCount(post.getBookmarkCount())
@@ -302,15 +303,15 @@ public List<BoardResponse> getParentBoards() {
     List<Board> parentBoards = boardRepository.findAllByParentBoardIsNull();
 
     return parentBoards.stream()
-        .map(BoardResponse::of)
+        .map(BoardResponse::from)
         .toList();
   }
 
   private PostResponse mapToPostResponse(Post post) {
     return PostResponse.builder()
         .postId(post.getPostId())
-        .user(post.getUser())
-        .board(post.getBoard())
+        .user(UserInfoResponse.from(post.getUser()))
+        .board(BoardResponse.from(post.getBoard()))
         .title(post.getTitle())
         .content(post.getContent())
         .bookmarkCount(post.getBookmarkCount())
diff --git a/backend/src/main/java/org/sejongisc/backend/user/dto/UserInfoResponse.java b/backend/src/main/java/org/sejongisc/backend/user/dto/UserInfoResponse.java
index 1c89f847..262631e3 100644
--- a/backend/src/main/java/org/sejongisc/backend/user/dto/UserInfoResponse.java
+++ b/backend/src/main/java/org/sejongisc/backend/user/dto/UserInfoResponse.java
@@ -1,11 +1,12 @@
 package org.sejongisc.backend.user.dto;
 
 import io.swagger.v3.oas.annotations.media.Schema;
-import lombok.AllArgsConstructor;
-import lombok.Getter;
-
 import java.util.Collection;
 import java.util.UUID;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import org.sejongisc.backend.common.auth.springsecurity.CustomUserDetails;
+import org.sejongisc.backend.user.entity.User;
 
 @Getter
 @AllArgsConstructor
@@ -56,4 +57,30 @@ public class UserInfoResponse {
             example = "[\"ROLE_USER\"]"
     )
     private Collection<?> authorities;
+
+  public static UserInfoResponse from(CustomUserDetails user) {
+    if (user == null) {
+      return null;
+    }
+
+    return new UserInfoResponse(
+        user.getUserId(),
+        user.getName(),
+        user.getEmail(),
+        user.getPhoneNumber(),
+        user.getPoint(),
+        user.getRole().name(),
+        user.getAuthorities()
+    );
+  }
+
+  public static UserInfoResponse from(User user) {
+    if (user == null) {
+      return null;
+    }
+
+    CustomUserDetails userDetails = new CustomUserDetails(user);
+
+    return from(userDetails);
+  }
 }
diff --git a/backend/src/test/java/org/sejongisc/backend/board/service/PostServiceImplTest.java b/backend/src/test/java/org/sejongisc/backend/board/service/PostServiceImplTest.java
index d94c7f77..d7cedc68 100644
--- a/backend/src/test/java/org/sejongisc/backend/board/service/PostServiceImplTest.java
+++ b/backend/src/test/java/org/sejongisc/backend/board/service/PostServiceImplTest.java
@@ -38,6 +38,7 @@
 import org.sejongisc.backend.common.exception.CustomException;
 import org.sejongisc.backend.common.exception.ErrorCode;
 import org.sejongisc.backend.user.dao.UserRepository;
+import org.sejongisc.backend.user.entity.Role; // Role Enum import 필요
 import org.sejongisc.backend.user.entity.User;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.PageImpl;
@@ -86,9 +87,28 @@ void setUp() {
     boardId = UUID.randomUUID();
     postId = UUID.randomUUID();
 
-    mockUser = User.builder().userId(userId).build();
-    mockParentBoard = Board.builder().boardId(UUID.randomUUID()).parentBoard(null).build();
-    mockBoard = Board.builder().boardId(boardId).parentBoard(mockParentBoard).build();
+    // DTO 변환(UserInfoResponse.from)시 NPE 방지를 위해 Role, Name, Email 등 필수 필드 세팅
+    mockUser = User.builder()
+        .userId(userId)
+        .email("test@example.com")
+        .name("Tester")
+        .role(Role.TEAM_MEMBER) // 또는 Role.USER (프로젝트 Enum 정의에 맞게)
+        .build();
+
+    mockParentBoard = Board.builder()
+        .boardId(UUID.randomUUID())
+        .boardName("Parent Board")
+        .parentBoard(null)
+        .createdBy(mockUser)
+        .build();
+
+    mockBoard = Board.builder()
+        .boardId(boardId)
+        .boardName("Child Board")
+        .parentBoard(mockParentBoard)
+        .createdBy(mockUser) // BoardResponse.from 호출 시 필요
+        .build();
+
     mockPost = Post.builder()
         .postId(postId)
         .user(mockUser)
@@ -118,7 +138,7 @@ void savePost_Success() {
     when(userRepository.findById(userId)).thenReturn(Optional.of(mockUser));
     when(fileUploadService.store(any(MultipartFile.class))).thenReturn("saved_filename.txt");
     when(fileUploadService.getRootLocation()).thenReturn(Paths.get("test/path"));
-    when(postRepository.save(any(Post.class))).thenReturn(mockPost); // 저장된 post 반환
+    when(postRepository.save(any(Post.class))).thenReturn(mockPost);
 
     // when
     postService.savePost(request, userId);
@@ -153,7 +173,7 @@ void updatePost_Success() {
     PostRequest request = PostRequest.builder()
         .title("Updated Title")
         .content("Updated Content")
-        .files(Collections.emptyList()) // 테스트 편의상 새 파일은 없음
+        .files(Collections.emptyList())
         .build();
 
     PostAttachment oldAttachment = PostAttachment.builder().savedFilename("old_file.txt").build();
@@ -180,11 +200,11 @@ void updatePost_Fail_InvalidOwner() {
     PostRequest request = PostRequest.builder().build();
 
     // Mocking
-    when(postRepository.findById(postId)).thenReturn(Optional.of(mockPost)); // mockPost의 user는 'userId'
+    when(postRepository.findById(postId)).thenReturn(Optional.of(mockPost));
 
     // when & then
     CustomException exception = assertThrows(CustomException.class, () -> {
-      postService.updatePost(request, postId, otherUserId); // 다른 'otherUserId'로 수정 시도
+      postService.updatePost(request, postId, otherUserId);
     });
 
     assertThat(exception.getErrorCode()).isEqualTo(ErrorCode.INVALID_POST_OWNER);
@@ -228,11 +248,16 @@ void getPosts_Success() {
     when(postRepository.findAllByBoard(mockBoard, pageable)).thenReturn(postPage);
 
     // when
+    // 여기서 mapToPostResponse 내부적으로 UserInfoResponse.from(), BoardResponse.from()이 호출됨
+    // mockUser에 Role 정보가 없으면 NPE 발생 가능 (setUp에서 처리함)
     Page<PostResponse> result = postService.getPosts(boardId, page, size);
 
     // then
     assertThat(result.getTotalElements()).isEqualTo(1);
     assertThat(result.getContent().get(0).getPostId()).isEqualTo(postId);
+    // DTO 변환 확인
+    assertThat(result.getContent().get(0).getUser().getName()).isEqualTo(mockUser.getName());
+    assertThat(result.getContent().get(0).getBoard().getBoardName()).isEqualTo(mockBoard.getBoardName());
   }
 
   @Test
@@ -244,8 +269,21 @@ void getPostDetail_Success_WithReplies() {
     Pageable commentPageable = PageRequest.of(page, size, Sort.by(Sort.Direction.ASC, "createdDate"));
 
     // 댓글 Mock 데이터 생성
-    Comment parentComment = Comment.builder().commentId(UUID.randomUUID()).post(mockPost).content("부모댓글1").parentComment(null).build();
-    Comment childComment = Comment.builder().commentId(UUID.randomUUID()).post(mockPost).content("대댓글1").parentComment(parentComment).build();
+    Comment parentComment = Comment.builder()
+        .commentId(UUID.randomUUID())
+        .post(mockPost)
+        .user(mockUser) // 댓글 작성자 필요 (DTO 변환 위해)
+        .content("부모댓글1")
+        .parentComment(null)
+        .build();
+
+    Comment childComment = Comment.builder()
+        .commentId(UUID.randomUUID())
+        .post(mockPost)
+        .user(mockUser) // 댓글 작성자 필요
+        .content("대댓글1")
+        .parentComment(parentComment)
+        .build();
 
     Page<Comment> parentCommentPage = new PageImpl<>(List.of(parentComment), commentPageable, 1);
 
@@ -293,8 +331,9 @@ void createBoard_Success() {
 
     // Mocking
     when(userRepository.findById(userId)).thenReturn(Optional.of(mockUser));
+    when(boardRepository.findById(mockParentBoard.getBoardId())).thenReturn(Optional.of(mockParentBoard));
 
-    // ArgumentCaptor: save(board)에 실제 어떤 board 객체가 전달되었는지 잡기 위함
+    // ArgumentCaptor
     ArgumentCaptor<Board> boardCaptor = ArgumentCaptor.forClass(Board.class);
 
     // when