diff --git a/src/main/java/com/sajang/devracebackend/controller/RoomController.java b/src/main/java/com/sajang/devracebackend/controller/RoomController.java
index cf5137a..9f886a0 100644
--- a/src/main/java/com/sajang/devracebackend/controller/RoomController.java
+++ b/src/main/java/com/sajang/devracebackend/controller/RoomController.java
@@ -1,7 +1,7 @@
 package com.sajang.devracebackend.controller;
 
-import com.sajang.devracebackend.dto.problem.ProblemRequestDto;
-import com.sajang.devracebackend.dto.room.RoomIdResponseDto;
+import com.sajang.devracebackend.dto.problem.ProblemSaveRequestDto;
+import com.sajang.devracebackend.dto.room.RoomSaveResponseDto;
 import com.sajang.devracebackend.response.ResponseCode;
 import com.sajang.devracebackend.response.ResponseData;
 import com.sajang.devracebackend.service.RoomService;
@@ -25,8 +25,8 @@ public class RoomController {
 
     @PostMapping("/rooms")
     @Operation(summary = "방 생성 [jwt O]")
-    public ResponseEntity<ResponseData<RoomIdResponseDto>> createRoom(@RequestBody ProblemRequestDto problemRequestDto) throws IOException {
-        RoomIdResponseDto roomIdResponseDto = roomService.createRoom(problemRequestDto);
-        return ResponseData.toResponseEntity(ResponseCode.CREATED_ROOM, roomIdResponseDto);
+    public ResponseEntity<ResponseData<RoomSaveResponseDto>> createRoom(@RequestBody ProblemSaveRequestDto problemSaveRequestDto) throws IOException {
+        RoomSaveResponseDto roomSaveResponseDto = roomService.createRoom(problemSaveRequestDto);
+        return ResponseData.toResponseEntity(ResponseCode.CREATED_ROOM, roomSaveResponseDto);
     }
 }
diff --git a/src/main/java/com/sajang/devracebackend/controller/UserController.java b/src/main/java/com/sajang/devracebackend/controller/UserController.java
index 4fa94f5..5f63146 100644
--- a/src/main/java/com/sajang/devracebackend/controller/UserController.java
+++ b/src/main/java/com/sajang/devracebackend/controller/UserController.java
@@ -1,6 +1,7 @@
 package com.sajang.devracebackend.controller;
 
-import com.sajang.devracebackend.dto.user.SolvedResponseDto;
+import com.sajang.devracebackend.dto.user.UserEnterResponseDto;
+import com.sajang.devracebackend.dto.user.UserSolvedResponseDto;
 import com.sajang.devracebackend.response.ResponseCode;
 import com.sajang.devracebackend.response.ResponseData;
 import com.sajang.devracebackend.service.UserService;
@@ -21,8 +22,15 @@ public class UserController {
 
     @GetMapping("/users/solved-count")
     @Operation(summary = "백준 solvedCount값 조회 [jwt O]")
-    public ResponseEntity<ResponseData<SolvedResponseDto>> checkUserSolvedCount() {
-        SolvedResponseDto solvedResponseDto = userService.checkUserSolvedCount();
-        return ResponseData.toResponseEntity(ResponseCode.READ_SOLVEDCOUNT, solvedResponseDto);
+    public ResponseEntity<ResponseData<UserSolvedResponseDto>> checkUserSolvedCount() {
+        UserSolvedResponseDto userSolvedResponseDto = userService.checkUserSolvedCount();
+        return ResponseData.toResponseEntity(ResponseCode.READ_SOLVEDCOUNT, userSolvedResponseDto);
+    }
+
+    @GetMapping("/users/rooms")
+    @Operation(summary = "참여중인 방 여부 검사 [jwt O]")
+    public ResponseEntity<ResponseData<UserEnterResponseDto>> findCurrentRoom() {
+        UserEnterResponseDto userEnterResponseDto = userService.findCurrentRoom();
+        return ResponseData.toResponseEntity(ResponseCode.READ_ROOM, userEnterResponseDto);
     }
 }
diff --git a/src/main/java/com/sajang/devracebackend/dto/problem/ProblemRequestDto.java b/src/main/java/com/sajang/devracebackend/dto/problem/ProblemSaveRequestDto.java
similarity index 83%
rename from src/main/java/com/sajang/devracebackend/dto/problem/ProblemRequestDto.java
rename to src/main/java/com/sajang/devracebackend/dto/problem/ProblemSaveRequestDto.java
index 2b71c51..993c105 100644
--- a/src/main/java/com/sajang/devracebackend/dto/problem/ProblemRequestDto.java
+++ b/src/main/java/com/sajang/devracebackend/dto/problem/ProblemSaveRequestDto.java
@@ -5,7 +5,7 @@
 
 @Getter
 @NoArgsConstructor
-public class ProblemRequestDto {
+public class ProblemSaveRequestDto {
 
     private Integer problemNumber;  // 백준 문제 번호
 }
diff --git a/src/main/java/com/sajang/devracebackend/dto/room/RoomIdResponseDto.java b/src/main/java/com/sajang/devracebackend/dto/room/RoomSaveResponseDto.java
similarity index 85%
rename from src/main/java/com/sajang/devracebackend/dto/room/RoomIdResponseDto.java
rename to src/main/java/com/sajang/devracebackend/dto/room/RoomSaveResponseDto.java
index c6f8d02..66e81a9 100644
--- a/src/main/java/com/sajang/devracebackend/dto/room/RoomIdResponseDto.java
+++ b/src/main/java/com/sajang/devracebackend/dto/room/RoomSaveResponseDto.java
@@ -7,7 +7,7 @@
 @Getter
 @NoArgsConstructor
 @AllArgsConstructor
-public class RoomIdResponseDto {
+public class RoomSaveResponseDto {
 
     private Long roomId;
 }
diff --git a/src/main/java/com/sajang/devracebackend/dto/user/UserEnterResponseDto.java b/src/main/java/com/sajang/devracebackend/dto/user/UserEnterResponseDto.java
new file mode 100644
index 0000000..f6fe118
--- /dev/null
+++ b/src/main/java/com/sajang/devracebackend/dto/user/UserEnterResponseDto.java
@@ -0,0 +1,14 @@
+package com.sajang.devracebackend.dto.user;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Getter
+@NoArgsConstructor
+@AllArgsConstructor
+public class UserEnterResponseDto {
+
+    private Boolean isEnter;  // 참여중인 방 존재 여부
+    private Long roomId;  // null 가능.
+}
diff --git a/src/main/java/com/sajang/devracebackend/dto/user/SolvedResponseDto.java b/src/main/java/com/sajang/devracebackend/dto/user/UserSolvedResponseDto.java
similarity index 72%
rename from src/main/java/com/sajang/devracebackend/dto/user/SolvedResponseDto.java
rename to src/main/java/com/sajang/devracebackend/dto/user/UserSolvedResponseDto.java
index 92667cf..a19eae9 100644
--- a/src/main/java/com/sajang/devracebackend/dto/user/SolvedResponseDto.java
+++ b/src/main/java/com/sajang/devracebackend/dto/user/UserSolvedResponseDto.java
@@ -6,12 +6,12 @@
 
 @Getter
 @NoArgsConstructor
-public class SolvedResponseDto {
+public class UserSolvedResponseDto {
 
     private Integer solvedCount;
 
     @Builder
-    public SolvedResponseDto(Integer solvedCount){
+    public UserSolvedResponseDto(Integer solvedCount){
         this.solvedCount = solvedCount;
     }
 }
diff --git a/src/main/java/com/sajang/devracebackend/service/RoomService.java b/src/main/java/com/sajang/devracebackend/service/RoomService.java
index e49c9d1..c71f834 100644
--- a/src/main/java/com/sajang/devracebackend/service/RoomService.java
+++ b/src/main/java/com/sajang/devracebackend/service/RoomService.java
@@ -1,10 +1,10 @@
 package com.sajang.devracebackend.service;
 
-import com.sajang.devracebackend.dto.problem.ProblemRequestDto;
-import com.sajang.devracebackend.dto.room.RoomIdResponseDto;
+import com.sajang.devracebackend.dto.problem.ProblemSaveRequestDto;
+import com.sajang.devracebackend.dto.room.RoomSaveResponseDto;
 
 import java.io.IOException;
 
 public interface RoomService {
-    RoomIdResponseDto createRoom(ProblemRequestDto problemRequestDto) throws IOException;
+    RoomSaveResponseDto createRoom(ProblemSaveRequestDto problemSaveRequestDto) throws IOException;
 }
diff --git a/src/main/java/com/sajang/devracebackend/service/UserService.java b/src/main/java/com/sajang/devracebackend/service/UserService.java
index 360f689..ebf34c6 100644
--- a/src/main/java/com/sajang/devracebackend/service/UserService.java
+++ b/src/main/java/com/sajang/devracebackend/service/UserService.java
@@ -1,9 +1,12 @@
 package com.sajang.devracebackend.service;
 
 import com.sajang.devracebackend.domain.User;
-import com.sajang.devracebackend.dto.user.SolvedResponseDto;
+import com.sajang.devracebackend.dto.user.UserEnterResponseDto;
+import com.sajang.devracebackend.dto.user.UserSolvedResponseDto;
 
 public interface UserService {
     User findUser(Long userId);
-    SolvedResponseDto checkUserSolvedCount();
+    User findLoginUser();
+    UserSolvedResponseDto checkUserSolvedCount();
+    UserEnterResponseDto findCurrentRoom();
 }
diff --git a/src/main/java/com/sajang/devracebackend/service/impl/AuthServiceImpl.java b/src/main/java/com/sajang/devracebackend/service/impl/AuthServiceImpl.java
index 387c180..c9b9c95 100644
--- a/src/main/java/com/sajang/devracebackend/service/impl/AuthServiceImpl.java
+++ b/src/main/java/com/sajang/devracebackend/service/impl/AuthServiceImpl.java
@@ -13,7 +13,6 @@
 import com.sajang.devracebackend.service.AuthService;
 import com.sajang.devracebackend.service.AwsS3Service;
 import com.sajang.devracebackend.service.UserService;
-import com.sajang.devracebackend.util.SecurityUtil;
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
@@ -44,13 +43,12 @@ public SignupResponseDto signup(MultipartFile imageFile, SignupRequestDto signup
         }
         UserServiceImpl.getSolvedCount(signupRequestDto.getBojId());  // solvedac 서버에 존재하지않는 백준id일경우 예외 처리.
 
-        Long loginUserId = SecurityUtil.getCurrentMemberId();
-        User user = userService.findUser(loginUserId);
+        User user = userService.findLoginUser();
 
         // signup은 Role이 GUEST인 사용자만 이용가능한 API임.
         if(!user.getRole().equals(Role.ROLE_GUEST) || user.getBojId() != null) {
             // 이 로직을 SecurityConfig의 hasAuthority("ROLE_GUEST") 외에도 여기 또 써줘야하는 이유는,
-            // reissue로 인한 재발급 이후에도 이전 엑세스 토큰으로 '/signup' 경로에 다시 접근할 경우, 토큰 내의 권한은 GUEST이 맞겠지만 DB 내의 권한은 USER이기에 이러한 비정상적인 접근을 방지할 수 있기 때문임.
+            // reissue로 인한 재발급 이후에도 이전 엑세스 토큰으로 '/signup' 경로에 다시 접근할 경우, 토큰 내의 권한은 GUEST가 맞겠지만 DB 내의 권한은 USER이기에 이러한 비정상적인 접근을 방지할 수 있기 때문임.
             throw new UserBadRequestException("이미 가입완료 되어있는 사용자입니다.");
         }
 
@@ -69,7 +67,7 @@ else if(imageFile != null && signupRequestDto.getIsImageChange() == 0) {  // 기
         UserResponseDto userResponseDto = new UserResponseDto(user);
 
         // 추가정보 입력후, 위에서 Role을 GUEST->USER로 업데이트했지만, 헤더의 jwt 토큰에 등록해둔 권한도 수정해야하기에, Access 토큰도 따로 재발급해야함.
-        TokenDto tokenDto = tokenProvider.generateAccessTokenByRefreshToken(loginUserId, Role.ROLE_USER, user.getRefreshToken());
+        TokenDto tokenDto = tokenProvider.generateAccessTokenByRefreshToken(user.getId(), Role.ROLE_USER, user.getRefreshToken());
 
         return new SignupResponseDto(userResponseDto, tokenDto);
     }
diff --git a/src/main/java/com/sajang/devracebackend/service/impl/RoomServiceImpl.java b/src/main/java/com/sajang/devracebackend/service/impl/RoomServiceImpl.java
index 1d29e76..c22c37a 100644
--- a/src/main/java/com/sajang/devracebackend/service/impl/RoomServiceImpl.java
+++ b/src/main/java/com/sajang/devracebackend/service/impl/RoomServiceImpl.java
@@ -2,8 +2,8 @@
 
 import com.sajang.devracebackend.domain.Problem;
 import com.sajang.devracebackend.domain.Room;
-import com.sajang.devracebackend.dto.problem.ProblemRequestDto;
-import com.sajang.devracebackend.dto.room.RoomIdResponseDto;
+import com.sajang.devracebackend.dto.problem.ProblemSaveRequestDto;
+import com.sajang.devracebackend.dto.room.RoomSaveResponseDto;
 import com.sajang.devracebackend.repository.ProblemRepository;
 import com.sajang.devracebackend.repository.RoomRepository;
 import com.sajang.devracebackend.service.ProblemService;
@@ -27,8 +27,8 @@ public class RoomServiceImpl implements RoomService {
 
     @Transactional
     @Override
-    public RoomIdResponseDto createRoom(ProblemRequestDto problemRequestDto) throws IOException {
-        Integer problemNumber = problemRequestDto.getProblemNumber();
+    public RoomSaveResponseDto createRoom(ProblemSaveRequestDto problemSaveRequestDto) throws IOException {
+        Integer problemNumber = problemSaveRequestDto.getProblemNumber();
 
         Problem problem = problemRepository.findByNumber(problemNumber)
                 .orElse(null);  // try~catch문 대신 null로 표현했음.
@@ -47,8 +47,8 @@ public RoomIdResponseDto createRoom(ProblemRequestDto problemRequestDto) throws
                 .problem(problem)
                 .build();
         Long roomId = roomRepository.save(room).getId();
-        RoomIdResponseDto roomIdResponseDto = new RoomIdResponseDto(roomId);
+        RoomSaveResponseDto roomSaveResponseDto = new RoomSaveResponseDto(roomId);
 
-        return roomIdResponseDto;
+        return roomSaveResponseDto;
     }
 }
diff --git a/src/main/java/com/sajang/devracebackend/service/impl/UserServiceImpl.java b/src/main/java/com/sajang/devracebackend/service/impl/UserServiceImpl.java
index b7d47f9..80d59f6 100644
--- a/src/main/java/com/sajang/devracebackend/service/impl/UserServiceImpl.java
+++ b/src/main/java/com/sajang/devracebackend/service/impl/UserServiceImpl.java
@@ -1,7 +1,9 @@
 package com.sajang.devracebackend.service.impl;
 
 import com.sajang.devracebackend.domain.User;
-import com.sajang.devracebackend.dto.user.SolvedResponseDto;
+import com.sajang.devracebackend.domain.mapping.UserRoom;
+import com.sajang.devracebackend.dto.user.UserEnterResponseDto;
+import com.sajang.devracebackend.dto.user.UserSolvedResponseDto;
 import com.sajang.devracebackend.repository.UserRepository;
 import com.sajang.devracebackend.response.exception.exception404.NoSuchBojIdException;
 import com.sajang.devracebackend.response.exception.exception404.NoSuchUserException;
@@ -14,6 +16,8 @@
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.web.reactive.function.client.WebClient;
 
+import java.util.Optional;
+
 @Service
 @RequiredArgsConstructor
 public class UserServiceImpl implements UserService {
@@ -30,19 +34,39 @@ public User findUser(Long userId) {
 
     @Transactional(readOnly = true)
     @Override
-    public SolvedResponseDto checkUserSolvedCount() {
+    public User findLoginUser() {
         Long loginUserId = SecurityUtil.getCurrentMemberId();
-        User user = findUser(loginUserId);
-        SolvedResponseDto solvedResponseDto = getSolvedCount(user.getBojId());
+        User loginUser = findUser(loginUserId);
+        return loginUser;
+    }
+
+    @Transactional(readOnly = true)
+    @Override
+    public UserSolvedResponseDto checkUserSolvedCount() {
+        User user = findLoginUser();
+        UserSolvedResponseDto userSolvedResponseDto = getSolvedCount(user.getBojId());
+
+        return userSolvedResponseDto;
+    }
+
+    @Transactional(readOnly = true)
+    @Override
+    public UserEnterResponseDto findCurrentRoom() {
+        User user = findLoginUser();
+
+        Optional<UserRoom> optionalUserRoom = user.getUserRoomList().stream()
+                .filter(userRoom -> userRoom.getIsLeave() == 0)  // getIsLeave() 값이 0인 경우만 필터링 (참여중인 방 찾기)
+                .findFirst();
+        UserRoom userRoom = optionalUserRoom.orElse(null);
 
-        return solvedResponseDto;
+        if(userRoom == null) return new UserEnterResponseDto(false, null);  // 참여중인 방이 없음 X.
+        else return new UserEnterResponseDto(true, userRoom.getRoom().getId());  // 참여중인 방이 있음 O.
     }
 
 
     // ========== 유틸성 메소드 ========== //
 
-    @Transactional
-    public static SolvedResponseDto getSolvedCount(String bojId){  // WebClient로 외부 solved API 호출 메소드
+    public static UserSolvedResponseDto getSolvedCount(String bojId){  // WebClient로 외부 solved API 호출 메소드
         try {
             WebClient webClient = WebClient.builder()
                     .baseUrl("https://solved.ac/api/v3")
@@ -52,7 +76,7 @@ public static SolvedResponseDto getSolvedCount(String bojId){  // WebClient로 
             return webClient.get()
                     .uri("/user/show?handle=" + bojId)
                     .retrieve()
-                    .bodyToMono(SolvedResponseDto.class)
+                    .bodyToMono(UserSolvedResponseDto.class)
                     .block();
         }catch (Exception e){
             throw new NoSuchBojIdException("bojId = " + bojId);  // solvedac 서버에 존재하지않는 백준id일경우 예외 처리.