diff --git a/src/main/java/com/example/pnuunivmiryangcampus/service/LoginService.java b/src/main/java/com/example/pnuunivmiryangcampus/service/LoginService.java
index e88b6e9..b33edd8 100644
--- a/src/main/java/com/example/pnuunivmiryangcampus/service/LoginService.java
+++ b/src/main/java/com/example/pnuunivmiryangcampus/service/LoginService.java
@@ -1,26 +1,58 @@
 package com.example.pnuunivmiryangcampus.service;
 
-import com.example.pnuunivmiryangcampus.auth.KakaoApiCaller;
+import com.example.pnuunivmiryangcampus.auth.KakaoInfoClient;
+import com.example.pnuunivmiryangcampus.auth.KakaoInformationResponse;
+import com.example.pnuunivmiryangcampus.auth.KakaoOauthClient;
 import com.example.pnuunivmiryangcampus.auth.KakaoProperties;
+import com.example.pnuunivmiryangcampus.auth.OIDCDecodePayload;
+import com.example.pnuunivmiryangcampus.auth.OauthOIDCHelper;
+import com.example.pnuunivmiryangcampus.domain.UserAccount;
 import com.example.pnuunivmiryangcampus.dto.KakaoTokenDto;
+import com.example.pnuunivmiryangcampus.dto.UserAccountDto;
+import com.example.pnuunivmiryangcampus.repository.UserAccountRepository;
+import java.util.Optional;
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
+@Slf4j
 @RequiredArgsConstructor
 @Transactional
 @Service
 public class LoginService {
 
-    private final KakaoApiCaller kakaoApiCaller;
+    private final KakaoOauthClient kakaoOauthClient;
+    private final KakaoInfoClient kakaoInfoClient;
     private final KakaoProperties kakaoProperties;
+    private final OauthOIDCHelper oauthOIDCHelper;
+    private final UserAccountRepository userAccountRepository;
 
     public KakaoTokenDto getKakaoToken(String code) {
-        return kakaoApiCaller.getKakaoToken(
+
+        return kakaoOauthClient.getKakaoToken(
                 kakaoProperties.getRestApiKey(),
                 kakaoProperties.getRedirectUri(),
                 code,
                 kakaoProperties.getGrantType()
         );
     }
+
+    public void isUserRegistered(KakaoTokenDto kakaoTokenDto) {
+
+        OIDCDecodePayload oidcDecodePayload = oauthOIDCHelper.getKakaoOIDCDecodePayload(kakaoTokenDto.idToken());
+        Optional<UserAccount> userAccount = userAccountRepository.findBySub(oidcDecodePayload.sub());
+
+        if (userAccount.isEmpty()) {
+            saveUserAccount(kakaoTokenDto);
+        }
+    }
+
+    private void saveUserAccount(KakaoTokenDto kakaoTokenDto) {
+
+        KakaoInformationResponse kakaoInformationResponse = kakaoInfoClient.kakaoUserInfo(kakaoTokenDto.tokenType() + " " + kakaoTokenDto.accessToken());
+        UserAccountDto userAccountDto = UserAccountDto.of(kakaoInformationResponse.nickname(), kakaoInformationResponse.email(), kakaoInformationResponse.sub());
+
+        userAccountRepository.save(userAccountDto.toEntity());
+    }
 }