diff --git a/src/main/java/toy/bookchat/bookchat/domain/chat/Sender.java b/src/main/java/toy/bookchat/bookchat/domain/chat/Sender.java
index ede3be6c..29bf19c4 100644
--- a/src/main/java/toy/bookchat/bookchat/domain/chat/Sender.java
+++ b/src/main/java/toy/bookchat/bookchat/domain/chat/Sender.java
@@ -7,20 +7,23 @@
 @Getter
 public class Sender {
 
-    private Long id;
-    private String nickname;
-    private String profileImageUrl;
-    private Integer defaultProfileImageType;
+  private Long id;
+  private String nickname;
+  private String profileImageUrl;
+  private Integer defaultProfileImageType;
 
-    @Builder
-    private Sender(Long id, String nickname, String profileImageUrl, Integer defaultProfileImageType) {
-        this.id = id;
-        this.nickname = nickname;
-        this.profileImageUrl = profileImageUrl;
-        this.defaultProfileImageType = defaultProfileImageType;
-    }
+  @Builder
+  private Sender(Long id, String nickname, String profileImageUrl, Integer defaultProfileImageType) {
+    this.id = id;
+    this.nickname = nickname;
+    this.profileImageUrl = profileImageUrl;
+    this.defaultProfileImageType = defaultProfileImageType;
+  }
 
-    public static Sender from(User user) {
-        return new Sender(user.getId(), user.getNickname(), user.getProfileImageUrl(), user.getDefaultProfileImageType());
+  public static Sender from(User user) {
+    if (user == null) {
+      return null;
     }
+    return new Sender(user.getId(), user.getNickname(), user.getProfileImageUrl(), user.getDefaultProfileImageType());
+  }
 }
diff --git a/src/main/java/toy/bookchat/bookchat/domain/chat/service/ChatReader.java b/src/main/java/toy/bookchat/bookchat/domain/chat/service/ChatReader.java
index 101df118..21a9cc65 100644
--- a/src/main/java/toy/bookchat/bookchat/domain/chat/service/ChatReader.java
+++ b/src/main/java/toy/bookchat/bookchat/domain/chat/service/ChatReader.java
@@ -19,44 +19,44 @@
 @Component
 public class ChatReader {
 
-    private final ChatRepository chatRepository;
-    private final UserReader userReader;
-
-    public ChatReader(ChatRepository chatRepository, UserReader userReader) {
-        this.chatRepository = chatRepository;
-        this.userReader = userReader;
-    }
-
-    public Chat readChat(Long userId, Long chatId) {
-        ChatEntity chatEntity = chatRepository.getUserChatRoomChat(chatId, userId).orElseThrow(ParticipantNotFoundException::new);
-        User user = userReader.readUser(userId);
-
-        Sender sender = Sender.from(user);
-
-        return Chat.builder()
-            .id(chatEntity.getId())
-            .chatRoomId(chatEntity.getChatRoomId())
-            .sender(sender)
-            .message(chatEntity.getMessage())
-            .dispatchTime(chatEntity.getCreatedAt())
-            .build();
-    }
-
-    public Slice<Chat> readSlicedChat(Long userId, Long roomId, Long postCursorId, Pageable pageable) {
-        Slice<ChatEntity> slicedChatEntity = chatRepository.getChatRoomChats(roomId, postCursorId, pageable, userId);
-        Map<Long, Long> chatIdUserIdMap = slicedChatEntity.stream().collect(Collectors.toMap(ChatEntity::getId, ChatEntity::getUserId));
-        List<Long> userIds = slicedChatEntity.stream().map(ChatEntity::getUserId).collect(Collectors.toList());
-        List<User> users = userReader.readUsers(userIds);
-        Map<Long, User> userIdUserMap = users.stream().collect(Collectors.toMap(User::getId, identity()));
-
-        return slicedChatEntity.map(sce ->
-            Chat.builder()
-                .id(sce.getId())
-                .chatRoomId(sce.getChatRoomId())
-                .sender(Sender.from(userIdUserMap.get(chatIdUserIdMap.get(sce.getId()))))
-                .message(sce.getMessage())
-                .dispatchTime(sce.getCreatedAt())
-                .build());
-    }
+  private final ChatRepository chatRepository;
+  private final UserReader userReader;
+
+  public ChatReader(ChatRepository chatRepository, UserReader userReader) {
+    this.chatRepository = chatRepository;
+    this.userReader = userReader;
+  }
+
+  public Chat readChat(Long userId, Long chatId) {
+    ChatEntity chatEntity = chatRepository.getUserChatRoomChat(chatId, userId)
+        .orElseThrow(ParticipantNotFoundException::new);
+    User user = userReader.readUser(userId);
+
+    Sender sender = Sender.from(user);
+
+    return Chat.builder()
+        .id(chatEntity.getId())
+        .chatRoomId(chatEntity.getChatRoomId())
+        .sender(sender)
+        .message(chatEntity.getMessage())
+        .dispatchTime(chatEntity.getCreatedAt())
+        .build();
+  }
+
+  public Slice<Chat> readSlicedChat(Long userId, Long roomId, Long postCursorId, Pageable pageable) {
+    Slice<ChatEntity> slicedChatEntity = chatRepository.getChatRoomChats(roomId, postCursorId, pageable, userId);
+    List<Long> userIds = slicedChatEntity.stream().map(ChatEntity::getUserId).collect(Collectors.toList());
+    List<User> users = userReader.readUsers(userIds);
+    Map<Long, User> userIdUserMap = users.stream().collect(Collectors.toMap(User::getId, identity()));
+
+    return slicedChatEntity.map(sce ->
+        Chat.builder()
+            .id(sce.getId())
+            .chatRoomId(sce.getChatRoomId())
+            .sender(Sender.from(userIdUserMap.get(sce.getUserId())))
+            .message(sce.getMessage())
+            .dispatchTime(sce.getCreatedAt())
+            .build());
+  }
 
 }
diff --git a/src/main/java/toy/bookchat/bookchat/localtest/rest/bookshelf/BookShelfAPI.http b/src/main/java/toy/bookchat/bookchat/localtest/rest/bookshelf/BookShelfAPI.http
index a8df5778..a6a7da57 100644
--- a/src/main/java/toy/bookchat/bookchat/localtest/rest/bookshelf/BookShelfAPI.http
+++ b/src/main/java/toy/bookchat/bookchat/localtest/rest/bookshelf/BookShelfAPI.http
@@ -1,7 +1,6 @@
 ### 서재에 책 등록
 POST localhost:8080/v1/api/bookshelves
-#Authorization: {{jwt_token}}
-Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJCb29rQ2hhdCIsImRlZmF1bHRQcm9maWxlSW1hZ2VUeXBlIjoxLCJwcm92aWRlciI6Imdvb2dsZSIsInVzZXJOaWNrbmFtZSI6Iu2VnOudvOu0iTIyIiwidXNlck5hbWUiOiIxMDE3MzM1MTIzNDA3MjA5ODU1OTRnb29nbGUiLCJ1c2VyUHJvZmlsZUltYWdlVXJpIjoiaHR0cHM6Ly9ib29rY2hhdC1vcmlnaW5hbC5zMy5hcC1ub3J0aGVhc3QtMi5hbWF6b25hd3MuY29tL3VzZXJfcHJvZmlsZV9pbWFnZS8zMi05MC00MjAyN2Q1MzJjNDAtZTliNi00M2FiLTljYTMtNzViMDQ1OWE2YzBjLndlYnAiLCJ1c2VyUm9sZSI6IlJPTEVfVVNFUiIsImV4cCI6MTcyODEzNzUzNCwidXNlcklkIjoiMSIsImVtYWlsIjpudWxsfQ.2HpnEuxn2IqiOnCUJATGe2sY62KgFdHDEUZ6H0wf5Qc
+Authorization: {{jwt_token}}
 Content-Type: application/json
 
 {
diff --git a/src/main/java/toy/bookchat/bookchat/localtest/rest/chat/ChatAPI.http b/src/main/java/toy/bookchat/bookchat/localtest/rest/chat/ChatAPI.http
index 57174fb4..5c04cc8e 100644
--- a/src/main/java/toy/bookchat/bookchat/localtest/rest/chat/ChatAPI.http
+++ b/src/main/java/toy/bookchat/bookchat/localtest/rest/chat/ChatAPI.http
@@ -1,2 +1,3 @@
 ### 채팅 조회
 GET localhost:8080/v1/api/chatrooms/1/chats?size=3
+Authorization: {{jwt_token}}