diff --git a/src/main/java/cnu/mvc/domain/member/MemberRepository.java b/src/main/java/cnu/mvc/domain/member/MemberRepository.java
index 1b273fc..902d5dc 100644
--- a/src/main/java/cnu/mvc/domain/member/MemberRepository.java
+++ b/src/main/java/cnu/mvc/domain/member/MemberRepository.java
@@ -22,7 +22,12 @@ public Member findById(Long id) {
 
     // 구현
     public Member findByEmail(String email) {
-        return null;
+        for (Member member : store.values()) {
+            if (member.getEmail().equals(email)) {
+                return member;
+            }
+        }
+        return null; // 해당 이메일을 가진 회원이 없으면 null 반환
     }
 }
 
diff --git a/src/main/java/cnu/mvc/domain/member/MemberService.java b/src/main/java/cnu/mvc/domain/member/MemberService.java
index b8e785e..01b4718 100644
--- a/src/main/java/cnu/mvc/domain/member/MemberService.java
+++ b/src/main/java/cnu/mvc/domain/member/MemberService.java
@@ -9,13 +9,21 @@ public class MemberService {
 
     private final MemberRepository memberRepository;
 
-    public Member join(Member member){
+    public Member join(Member member) {
+        // 이메일 중복 검사
+        Member existingMember = memberRepository.findByEmail(member.getEmail());
+        if (existingMember != null) {
+            throw new IllegalStateException("이미 존재하는 이메일입니다."); // 예외 발생
+        }
         return memberRepository.save(member);
     }
 
     public Member validateMember(String email, String pwd) {
-        Member findMember = findById(1L);
-        return findMember;
+        Member findMember = findByEmail(email);
+    if (findMember == null || !findMember.getPwd().equals(pwd)) {
+        throw new IllegalArgumentException("이메일 또는 비밀번호를 확인해주세요."); // ✅ 로그인 검증 실패
+    }
+    return findMember;
     }
 
     public Member findById(Long id) {