diff --git a/src/main/java/cnu/mvc/domain/member/MemberRepository.java b/src/main/java/cnu/mvc/domain/member/MemberRepository.java
index 1b273fc..aaf0174 100644
--- a/src/main/java/cnu/mvc/domain/member/MemberRepository.java
+++ b/src/main/java/cnu/mvc/domain/member/MemberRepository.java
@@ -1,16 +1,11 @@
 package cnu.mvc.domain.member;
-
 import org.springframework.stereotype.Repository;
-
 import java.util.HashMap;
 import java.util.Map;
-
 @Repository
 public class MemberRepository {
-
     private static final Map<Long, Member> store = new HashMap<>();
     private static long sequence = 0L;
-
     public Member save(Member member) {
         member.setId(++sequence);
         store.put(member.getId(), member);
@@ -19,10 +14,12 @@ public Member save(Member member) {
     public Member findById(Long id) {
         return store.get(id);
     }
-
-    // 구현
     public Member findByEmail(String email) {
+        for(Member m :store.values()){
+            if(m.getEmail().equals(email)){
+                return m;
+            }
+        }
         return null;
     }
-}
-
+}
\ No newline at end of file
diff --git a/src/main/java/cnu/mvc/domain/member/MemberService.java b/src/main/java/cnu/mvc/domain/member/MemberService.java
index b8e785e..d2094bd 100644
--- a/src/main/java/cnu/mvc/domain/member/MemberService.java
+++ b/src/main/java/cnu/mvc/domain/member/MemberService.java
@@ -1,30 +1,36 @@
 package cnu.mvc.domain.member;
-
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
-
 @Service
 @RequiredArgsConstructor
 public class MemberService {
-
     private final MemberRepository memberRepository;
 
-    public Member join(Member member){
+    public Member save(Member member){
         return memberRepository.save(member);
     }
+    public Member findById(Long id) {
+        return memberRepository.findById(id);
+    }
 
     public Member validateMember(String email, String pwd) {
-        Member findMember = findById(1L);
+        Member findMember = memberRepository.findByEmail(email);
+        if(findMember == null || !findMember.getPwd().equals(pwd)){
+            throw new IllegalStateException("이메일 또는 비밀번호를 확인해주세요.");
+        }
         return findMember;
     }
 
-    public Member findById(Long id) {
-        return memberRepository.findById(id);
+    public Member join(Member member) {
+        validateMember(member.getEmail());
+        return memberRepository.save(member);
     }
 
-    // 구현
-    public Member findByEmail(String email) {
-        return memberRepository.findByEmail(email);
+    private void validateMember(String email) {
+        Member existing = memberRepository.findByEmail(email);
+        if(existing != null){
+            throw new IllegalStateException("이미 존재하는 이메일 계정입니다.");
+        }
     }
 
-}
+}
\ No newline at end of file