diff --git a/firstSeminarAdvancedAssignment/docs/readme.md b/firstSeminarAdvancedAssignment/docs/readme.md
index 69f7be0..bcc3e92 100644
--- a/firstSeminarAdvancedAssignment/docs/readme.md
+++ b/firstSeminarAdvancedAssignment/docs/readme.md
@@ -5,7 +5,7 @@
 - [X] 고객 등록 기능
   + [X] 계좌번호 등록
     * 기본 금액은 0원으로 설정
-    * [ ] ⚠️ 이미 존재하는 계좌번호 등록 시, 예외발생
+    * [X] ⚠️ 이미 존재하는 계좌번호 등록 시, 예외발생
   + [X] 개인정보 등록(이름,생년월일,전화번호,주소)
   + [X] 비밀번호 등록
 - [ ] 잔액 조회 기능
diff --git a/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/FirstSeminarAdvancedAssignmentApplication.java b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/FirstSeminarAdvancedAssignmentApplication.java
index dc89c91..e16c665 100644
--- a/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/FirstSeminarAdvancedAssignmentApplication.java
+++ b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/FirstSeminarAdvancedAssignmentApplication.java
@@ -6,8 +6,9 @@
 @SpringBootApplication
 public class FirstSeminarAdvancedAssignmentApplication {
 
-	public static void main(String[] args) {
-		SpringApplication.run(FirstSeminarAdvancedAssignmentApplication.class, args);
-	}
+    public static void main(String[] args) {
+        SpringApplication.run(FirstSeminarAdvancedAssignmentApplication.class, args);
+
+    }
 
 }
diff --git a/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/controller/ClientController.java b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/controller/ClientController.java
new file mode 100644
index 0000000..0c6decf
--- /dev/null
+++ b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/controller/ClientController.java
@@ -0,0 +1,18 @@
+package sopt.org.firstSeminarAdvancedAssignment.controller;
+
+import sopt.org.firstSeminarAdvancedAssignment.service.ClientService;
+import sopt.org.firstSeminarAdvancedAssignment.view.InputView;
+import sopt.org.firstSeminarAdvancedAssignment.view.OutputView;
+
+public class ClientController {
+    private final ClientService clientService = new ClientService();
+    private final InputView inputView = new InputView();
+    private final OutputView outputView = new OutputView();
+
+
+    public void registerClient() {
+        outputView.inputClientInfoMessage();
+        clientService.registerClient(inputView.inputAccountNumber(), inputView.inputClientName(), inputView.inputBirth(), inputView.inputTel(), inputView.inputAddress(), inputView.inputPassword());
+    }
+
+}
diff --git a/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/domain/Client.java b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/domain/Client.java
new file mode 100644
index 0000000..cf6cb9b
--- /dev/null
+++ b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/domain/Client.java
@@ -0,0 +1,28 @@
+package sopt.org.firstSeminarAdvancedAssignment.domain;
+
+public class Client {
+
+    private String accountNumber;
+    private String password;
+
+    private int amount;
+    private String name;
+    private String birth;
+    private String tel;
+    private String address;
+
+
+    public Client(String accountNumber, String password, String name, String birth, String tel, String address) {
+        this.accountNumber = accountNumber;
+        this.password = password;
+        this.name = name;
+        this.birth = birth;
+        this.tel = tel;
+        this.address = address;
+        this.amount = 0;
+    }
+
+    public String getAccountNumber() {
+        return accountNumber;
+    }
+}
diff --git a/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/repository/ClientRepository.java b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/repository/ClientRepository.java
new file mode 100644
index 0000000..ccdf261
--- /dev/null
+++ b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/repository/ClientRepository.java
@@ -0,0 +1,29 @@
+package sopt.org.firstSeminarAdvancedAssignment.repository;
+
+import sopt.org.firstSeminarAdvancedAssignment.domain.Client;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import static sopt.org.firstSeminarAdvancedAssignment.view.TextData.ACCOUNT_NUMBER_DUPLICATED_ERROR_MESSAGE;
+
+public class ClientRepository {
+    private static final Map<String, Client> clientDB = new LinkedHashMap<>();
+
+    public void register(Client client) {
+        boolean isDuplicated = false;
+
+        for (String accountNumber : clientDB.keySet()) {
+            if (client.getAccountNumber().equals(accountNumber)) {
+                isDuplicated = true;
+                break;
+            }
+        }
+
+        if (isDuplicated) {
+            throw new IllegalArgumentException(ACCOUNT_NUMBER_DUPLICATED_ERROR_MESSAGE);
+        }
+
+        clientDB.put(client.getAccountNumber(), client);
+    }
+}
diff --git a/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/service/ClientService.java b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/service/ClientService.java
new file mode 100644
index 0000000..3f03fdc
--- /dev/null
+++ b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/service/ClientService.java
@@ -0,0 +1,13 @@
+package sopt.org.firstSeminarAdvancedAssignment.service;
+
+import sopt.org.firstSeminarAdvancedAssignment.domain.Client;
+import sopt.org.firstSeminarAdvancedAssignment.repository.ClientRepository;
+
+public class ClientService {
+    private final ClientRepository clientRepository = new ClientRepository();
+
+    public void registerClient(String accountNumber, String name, String birth, String tel, String address, String password) {
+        Client client = new Client(accountNumber, name, birth, tel, address, password);
+        clientRepository.register(client);
+    }
+}
diff --git a/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/view/InputView.java b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/view/InputView.java
new file mode 100644
index 0000000..ee05606
--- /dev/null
+++ b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/view/InputView.java
@@ -0,0 +1,43 @@
+package sopt.org.firstSeminarAdvancedAssignment.view;
+
+import java.util.Scanner;
+
+public class InputView {
+    private Scanner sc = new Scanner(System.in);
+    private final OutputView outputView = new OutputView();
+
+    public String inputAccountNumber() {
+        outputView.inputAccountNumberForRegisterMessage();
+        return inputString();
+    }
+
+    public String inputClientName() {
+        outputView.inputClientNameForRegisterMessage();
+        return inputString();
+    }
+
+    public String inputPassword() {
+        outputView.inputPasswordForRegisterMessage();
+        return inputString();
+    }
+
+    public String inputBirth() {
+        outputView.inputBirthForRegisterMessage();
+        return inputString();
+    }
+
+    public String inputTel() {
+        outputView.inputTelNumberForRegisterMessage();
+        return inputString();
+    }
+
+    public String inputAddress() {
+        outputView.inputAddressForRegisterMessage();
+        return inputString();
+    }
+
+
+    private String inputString() {
+        return sc.nextLine();
+    }
+}
diff --git a/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/view/OutputView.java b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/view/OutputView.java
new file mode 100644
index 0000000..ce87ee8
--- /dev/null
+++ b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/view/OutputView.java
@@ -0,0 +1,33 @@
+package sopt.org.firstSeminarAdvancedAssignment.view;
+
+public class OutputView {
+
+    public final void inputClientInfoMessage() {
+        System.out.println("고객 등록을 위하여, 정보를 입력해주세요.");
+    }
+
+    public final void inputAccountNumberForRegisterMessage() {
+        System.out.println("등록하실 계좌번호를 입력해주세요. (중복불가)");
+    }
+
+    public final void inputClientNameForRegisterMessage() {
+        System.out.println("이름을 입력해주세요.");
+    }
+
+    public final void inputBirthForRegisterMessage() {
+        System.out.println("생년월일을 입력해주세요. (2000-01-01 형식)");
+    }
+
+    public final void inputTelNumberForRegisterMessage() {
+        System.out.println("전화번호를 입력해주세요. (010-1234-1234 형식)");
+    }
+
+    public final void inputAddressForRegisterMessage() {
+        System.out.println("거주지 주소를 입력해주세요.");
+    }
+
+    public final void inputPasswordForRegisterMessage() {
+        System.out.println("사용하실 비밀번호를 입력해주세요.");
+    }
+
+}
diff --git a/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/view/TextData.java b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/view/TextData.java
new file mode 100644
index 0000000..a642a92
--- /dev/null
+++ b/firstSeminarAdvancedAssignment/src/main/java/sopt/org/firstSeminarAdvancedAssignment/view/TextData.java
@@ -0,0 +1,6 @@
+package sopt.org.firstSeminarAdvancedAssignment.view;
+
+public class TextData {
+
+    public static final String ACCOUNT_NUMBER_DUPLICATED_ERROR_MESSAGE = "이미 존재하는 계좌번호입니다. 다른 번호를 사용해주세요.";
+}