diff --git a/src/main/java/com/project/coalba/domain/auth/repository/UserRepository.java b/src/main/java/com/project/coalba/domain/auth/repository/UserRepository.java
index 52e78f8..7b1d375 100644
--- a/src/main/java/com/project/coalba/domain/auth/repository/UserRepository.java
+++ b/src/main/java/com/project/coalba/domain/auth/repository/UserRepository.java
@@ -6,6 +6,6 @@
 
 import java.util.Optional;
 
-public interface UserRepository extends JpaRepository<User, Long> {
+public interface UserRepository extends JpaRepository<User, Long>, UserRepositoryCustom {
     Optional<User> findByProviderIdAndRole(String providerId, Role role);
 }
diff --git a/src/main/java/com/project/coalba/domain/auth/repository/UserRepositoryCustom.java b/src/main/java/com/project/coalba/domain/auth/repository/UserRepositoryCustom.java
new file mode 100644
index 0000000..d1ddd22
--- /dev/null
+++ b/src/main/java/com/project/coalba/domain/auth/repository/UserRepositoryCustom.java
@@ -0,0 +1,5 @@
+package com.project.coalba.domain.auth.repository;
+
+public interface UserRepositoryCustom {
+    Boolean existsByProfile(Long userId);
+}
diff --git a/src/main/java/com/project/coalba/domain/auth/repository/impl/UserRepositoryImpl.java b/src/main/java/com/project/coalba/domain/auth/repository/impl/UserRepositoryImpl.java
new file mode 100644
index 0000000..66666e9
--- /dev/null
+++ b/src/main/java/com/project/coalba/domain/auth/repository/impl/UserRepositoryImpl.java
@@ -0,0 +1,34 @@
+package com.project.coalba.domain.auth.repository.impl;
+
+import com.project.coalba.domain.auth.entity.enums.Role;
+import com.project.coalba.domain.auth.repository.UserRepositoryCustom;
+import com.querydsl.jpa.JPAExpressions;
+import com.querydsl.jpa.impl.JPAQueryFactory;
+import lombok.RequiredArgsConstructor;
+
+import static com.project.coalba.domain.auth.entity.QUser.*;
+import static com.project.coalba.domain.profile.entity.QBoss.*;
+import static com.project.coalba.domain.profile.entity.QStaff.*;
+
+@RequiredArgsConstructor
+public class UserRepositoryImpl implements UserRepositoryCustom {
+    private final JPAQueryFactory queryFactory;
+
+    @Override
+    public Boolean existsByProfile(Long userId) {
+        return queryFactory.selectFrom(user)
+                .where(user.id.eq(userId),
+                        user.role.eq(Role.BOSS).and(
+                                JPAExpressions.selectFrom(boss)
+                                        .where(boss.user.id.eq(userId))
+                                        .exists()
+                        ).or(user.role.eq(Role.STAFF).and(
+                                JPAExpressions.selectFrom(staff)
+                                        .where(staff.user.id.eq(userId))
+                                        .exists()
+                                )
+                        )
+                )
+                .fetchOne() != null;
+    }
+}
diff --git a/src/main/java/com/project/coalba/domain/auth/service/AuthService.java b/src/main/java/com/project/coalba/domain/auth/service/AuthService.java
index 4f1a635..8df1f40 100644
--- a/src/main/java/com/project/coalba/domain/auth/service/AuthService.java
+++ b/src/main/java/com/project/coalba/domain/auth/service/AuthService.java
@@ -26,16 +26,13 @@ public class AuthService {
     @Transactional
     public AuthResponse login(SocialInfo socialInfo, Role role) {
         Optional<User> userOptional = getSubscribedUser(socialInfo.getProviderId(), role);
-        boolean isNewUser = userOptional.isEmpty();
-
-        User loginUser;
-        if (isNewUser) loginUser = joinUser(socialInfo, role);
-        else loginUser = updateUser(userOptional.get(), socialInfo);
+        User loginUser = userOptional.map(user -> updateUser(user, socialInfo))
+                .orElseGet(() -> joinUser(socialInfo, role));
 
         String accessToken = tokenManager.createAccessToken(loginUser.getProviderId(), loginUser.getId());
         String refreshToken = issueRefreshToken(getUserRefreshToken(loginUser.getId()).orElse(null));
         manageRefreshToken(loginUser, refreshToken);
-        return new AuthResponse(accessToken, refreshToken, isNewUser);
+        return new AuthResponse(accessToken, refreshToken, isNewUser(loginUser.getId()));
     }
 
     @Transactional
@@ -70,6 +67,10 @@ private User updateUser(User user, SocialInfo socialInfo) {
         return user;
     }
 
+    private Boolean isNewUser(Long userId) {
+        return userRepository.existsByProfile(userId);
+    }
+
     private void manageRefreshToken(User loginUser, String refreshToken) {
         Optional<UserRefreshToken> userRefreshTokenOptional = getUserRefreshToken(loginUser.getId());
         userRefreshTokenOptional.ifPresentOrElse(userRefreshToken -> userRefreshToken.updateToken(refreshToken),