diff --git a/src/main/java/com/dnd/dndtravel/map/repository/WithdrawMemberRepository.java b/src/main/java/com/dnd/dndtravel/map/repository/WithdrawMemberRepository.java
index c3bde08..32ca6ef 100644
--- a/src/main/java/com/dnd/dndtravel/map/repository/WithdrawMemberRepository.java
+++ b/src/main/java/com/dnd/dndtravel/map/repository/WithdrawMemberRepository.java
@@ -8,4 +8,8 @@
 
 public interface WithdrawMemberRepository extends JpaRepository<WithdrawMember, Long> {
 	Optional<WithdrawMember> findByAppleId(String sub);
+
+	String findByEmail(String email);
+
+	boolean existsByAppleId(String sub);
 }
diff --git a/src/main/java/com/dnd/dndtravel/member/service/MemberService.java b/src/main/java/com/dnd/dndtravel/member/service/MemberService.java
index f5165a1..bea36fe 100644
--- a/src/main/java/com/dnd/dndtravel/member/service/MemberService.java
+++ b/src/main/java/com/dnd/dndtravel/member/service/MemberService.java
@@ -1,7 +1,5 @@
 package com.dnd.dndtravel.member.service;
 
-import java.util.Optional;
-
 import com.dnd.dndtravel.auth.repository.RefreshTokenRepository;
 import com.dnd.dndtravel.map.exception.MemberNotFoundException;
 import com.dnd.dndtravel.map.repository.MemberAttractionRepository;
@@ -9,7 +7,6 @@
 import com.dnd.dndtravel.auth.service.MemberNameGenerator;
 import com.dnd.dndtravel.map.repository.WithdrawMemberRepository;
 import com.dnd.dndtravel.member.domain.Member;
-import com.dnd.dndtravel.member.domain.WithdrawMember;
 import com.dnd.dndtravel.member.repository.MemberRepository;
 import com.dnd.dndtravel.member.service.response.MyPageResponse;
 
@@ -30,18 +27,33 @@ public class MemberService {
     private final WithdrawMemberRepository withDrawMemberRepository;
     private final MemberNameGenerator memberNameGenerator;
 
+    /**
+     * 1. 탈퇴후 재가입 유저의 email이 null인경우
+     * => withDraw 테이블을 조회후 최초 로그인시 저장했던 sub값으로 유저 판별후 sub값에 해당하는 email 가져와 DB에 저장
+     *
+     * 2. 탈퇴후 재가입 유저의 email이 존재하는경우
+     * => 해당 email로 withDraw 테이블을 조회후, 해당하는 email 가져와 DB에 저장
+     *
+     * 3. 최초 로그인 유저의 email이 null인경우
+     * => 가입 시켜줄수 없음 (예외)
+     *
+     * 4. 최초 로그인 유저의 email이 존재하는경우
+     * => 해당 email로 withDraw 테이블 조회후, email존재여부를 확인하고 없으므로 입력받은 email을 DB에 저장
+     */
     @Transactional
     public Member saveMember(String email, String sub, String selectedColor) {
         // 재가입 유저
         log.info("email = {}", email);
         log.info("sub = {}", sub);
-        String targetEmail = Optional.ofNullable(email).orElseGet(() -> getWithdrawMemberEmail(sub));
-        if (isNewLoginMember(email)) {
-            withDrawMemberRepository.save(WithdrawMember.of(sub, email));
-        }
-
-        return memberRepository.findByEmail(targetEmail)
-                .orElseGet(() -> memberRepository.save(Member.of(memberNameGenerator.generateRandomName(), targetEmail,selectedColor)));
+        validateNewMemberEmail(email, sub);
+        String targetEmail = determineEmail(email, sub);
+        return memberRepository.save(
+            Member.of(
+                memberNameGenerator.generateRandomName(),
+                targetEmail,
+                selectedColor
+            )
+        );
     }
 
     @Transactional
@@ -68,7 +80,21 @@ private String getWithdrawMemberEmail(String sub) {
             .getEmail();
     }
 
-    private boolean isNewLoginMember(String email) {
-        return email != null;
+    private String determineEmail(String email, String sub) {
+        // 케이스 1: 탈퇴 후 재가입 유저 (이메일 없음)
+        if (email == null) {
+            return getWithdrawMemberEmail(sub);
+        }
+
+        // 케이스 2, 4: 이메일이 있는 경우
+        String withdrawnEmail = withDrawMemberRepository.findByEmail(email);
+        return withdrawnEmail == null ? email : withdrawnEmail;
+    }
+
+    private void validateNewMemberEmail(String email, String sub) {
+        // 최로 로그인 유저인데 IdToken의 email도 null인경우 (케이스 3)
+        if (email == null && withDrawMemberRepository.existsByAppleId(sub)) {
+            throw new MemberNotFoundException(sub);
+        }
     }
 }