diff --git a/src/main/java/cnu/mvc/domain/member/MemberRepository.java b/src/main/java/cnu/mvc/domain/member/MemberRepository.java
index 1b273fc..422f4f9 100644
--- a/src/main/java/cnu/mvc/domain/member/MemberRepository.java
+++ b/src/main/java/cnu/mvc/domain/member/MemberRepository.java
@@ -16,13 +16,18 @@ public Member save(Member member) {
         store.put(member.getId(), member);
         return member;
     }
+
     public Member findById(Long id) {
         return store.get(id);
     }
 
-    // 구현
+    // 1-1) 이메일로 회원 조회
     public Member findByEmail(String email) {
+        for (Member member : store.values()) {
+            if (member.getEmail().equals(email)) {
+                return member;
+            }
+        }
         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..2ba7cd7 100644
--- a/src/main/java/cnu/mvc/domain/member/MemberService.java
+++ b/src/main/java/cnu/mvc/domain/member/MemberService.java
@@ -9,22 +9,29 @@ public class MemberService {
 
     private final MemberRepository memberRepository;
 
-    public Member join(Member member){
+    // 1-2) 회원가입 시 중복 이메일 검증
+    public Member join(Member member) {
+        if (memberRepository.findByEmail(member.getEmail()) != null) {
+            throw new IllegalStateException("이미 존재하는 이메일 계정입니다.");
+        }
         return memberRepository.save(member);
     }
 
+    // 2-1) 로그인 검증
     public Member validateMember(String email, String pwd) {
-        Member findMember = findById(1L);
+        Member findMember = memberRepository.findByEmail(email);
+        if (findMember == null || !findMember.getPassword().equals(pwd)) {
+            throw new IllegalArgumentException("이메일 또는 비밀번호를 확인해주세요.");
+        }
         return findMember;
     }
 
+    // 기타 기능
     public Member findById(Long id) {
         return memberRepository.findById(id);
     }
 
-    // 구현
     public Member findByEmail(String email) {
         return memberRepository.findByEmail(email);
     }
-
 }