diff --git a/README.md b/README.md
index bd90ef024..28b3d5439 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,57 @@
-# java-calculator-precourse
\ No newline at end of file
+# java-calculator-precourse
+## 기능 구현 목록
+입력한 문자열에서 숫자를 추출하여 더하는 계산기를 구현한다.
+
+### 입력
+- [X] 유저의 입력을 전달한다.
+
+### 입력값 검사기
+- 커스텀 구분자가 있는 입력일 때
+    - [X] 커스텀 구분자가 `//`로 시작해 `\n`가 포함되는지 확인한다.
+    - [X] 커스텀 구분자가 길이가 1이 아니라면 예외 처리한다.
+    - [X] 커스텀 구분자가 숫자라면 예외 처리한다.
+    - [X] 커스텀 구분자가 실수를 표현하는 `.`라면 예외 처리한다.
+    - [X] 커스텀 구분자가 기본 구분자라면 예외 처리 한다.
+
+
+- 커스텀 구분자가 없을 입력일 때
+    - [X] 입력값이 숫자로 시작하는 지 확인한다.
+
+
+- 공통
+    - [X] 커스텀 구분자를 입력하려는지 확인한다.
+    - [X] 음수가 입력되었다면 예외 처리 한다.
+    - [X] 구분자, `.`, 숫자 외 문자가 검출 된다면 예외 처리한다.
+
+### 구분자 관리
+- [X] 기본 구분자 외 커스텀 구분자를 전달받아 추가한다.
+- [X] 전달받은 구분자가 기본(이미 존재하는지) 구분자인지 확인한다.
+- [X] 구분자를 넘겨준다.
+
+### 문자열 핸들러
+- [X] 커스텀 구분자를 선언한다면 분리한다.
+- [X] 분리한 커스텀 구분자를 넘겨준다.
+- [X] 전달받은 구분자로 입력받은 문자열을 분리한다.
+
+### 덧셈기
+- [X] 전달 받은 값을 더해 저장한다.
+- [X] 저장한 결과 값을 전달한다.
+- [X] 입력값이 출력 범위를 초과한다면 예외 처리한다.
+- [X] 더한 값이 출력 범위를 초과한다면 예외 처리한다.
+
+### 출력
+- [X] 시작 메세지를 출력한다.
+- [X] 결과값을 출력한다.
+
+---
+## 리팩토링
+
+- [X] 하드 코딩 제거
+- [X] 코딩 컨벤션 준수
+- [X] 이상한 수식 넣었을 때 에러
+  ```
+  덧셈할 문자열을 입력해 주세요.
+  //;\n112kio12u328948
+  Exception in thread "main" java.lang.NumberFormatException: For input string: "112kio12u328948"
+  ```
+- [ ] 기능 쪼개기 
\ No newline at end of file
diff --git a/src/main/java/calculator/Application.java b/src/main/java/calculator/Application.java
index 573580fb4..12f94718c 100644
--- a/src/main/java/calculator/Application.java
+++ b/src/main/java/calculator/Application.java
@@ -2,6 +2,7 @@
 
 public class Application {
     public static void main(String[] args) {
-        // TODO: 프로그램 구현
+        Controller controller = new Controller();
+        controller.start();
     }
 }
diff --git a/src/main/java/calculator/Controller.java b/src/main/java/calculator/Controller.java
new file mode 100644
index 000000000..1015c1bfa
--- /dev/null
+++ b/src/main/java/calculator/Controller.java
@@ -0,0 +1,46 @@
+package calculator;
+
+import calculator.util.Adder;
+import calculator.util.SeparatorManager;
+import calculator.util.StringHandler;
+import calculator.util.Validator;
+import java.util.List;
+
+public class Controller {
+    Input input = new Input();
+    Output output = new Output();
+    SeparatorManager separatorManager = new SeparatorManager();
+    StringHandler stringHandler = new StringHandler();
+    Validator validator = new Validator();
+    Adder adder = new Adder();
+
+    public void start() {
+        output.printStart();
+        String userInput = input.readInput();
+        validator.validateInput(userInput);
+
+        if (validator.hasCustomSeparator(userInput)) {
+            String separator = stringHandler.extractSeparator(userInput);
+            validator.validateSeparator(separator);
+            separatorManager.add(separator);
+            String rawNumbers = stringHandler.removeCustom(userInput);
+            List<String> numbers = stringHandler.getNumbers(
+                    separatorManager.getSeparators(),
+                    rawNumbers);
+            adder.add(numbers);
+            output.printResult(adder.getAnswer());
+            return;
+        }
+
+        if (validator.isStartWithDigit(userInput)) {
+            List<String> numbers =  stringHandler.getNumbers(
+                    separatorManager.getSeparators(),
+                    userInput
+            );
+            adder.add(numbers);
+            output.printResult(adder.getAnswer());
+            return;
+        }
+        output.printResult(adder.getAnswer());
+    }
+}
diff --git a/src/main/java/calculator/Input.java b/src/main/java/calculator/Input.java
new file mode 100644
index 000000000..2476bdead
--- /dev/null
+++ b/src/main/java/calculator/Input.java
@@ -0,0 +1,9 @@
+package calculator;
+
+import camp.nextstep.edu.missionutils.Console;
+
+public class Input {
+    public String readInput() {
+        return Console.readLine();
+    }
+}
diff --git a/src/main/java/calculator/Output.java b/src/main/java/calculator/Output.java
new file mode 100644
index 000000000..ad987a132
--- /dev/null
+++ b/src/main/java/calculator/Output.java
@@ -0,0 +1,11 @@
+package calculator;
+
+public class Output {
+    public void printStart() {
+        System.out.println("덧셈할 문자열을 입력해 주세요.");
+    }
+
+    public void printResult(long result) {
+        System.out.println("결과 : " + result);
+    }
+}
diff --git a/src/main/java/calculator/util/Adder.java b/src/main/java/calculator/util/Adder.java
new file mode 100644
index 000000000..5ec67194d
--- /dev/null
+++ b/src/main/java/calculator/util/Adder.java
@@ -0,0 +1,39 @@
+package calculator.util;
+
+import java.util.List;
+
+public class Adder {
+    long answer;
+
+    public void add(List<String> numbers) {
+        answer = 0;
+        for (String number: numbers) {
+            if (number.isBlank()) {
+                continue;
+            }
+            validateNumber(number);
+            long element = Long.parseLong(number);
+            validateOverflow(element);
+            answer += element;
+        }
+        validateOverflow(answer);
+    }
+
+    public long getAnswer() {
+        return answer;
+    }
+
+    private void validateOverflow(long number) {
+        if (number < 0) {
+            throw new IllegalArgumentException("허용 범위를 초과하였습니다.");
+        }
+    }
+
+    private void validateNumber(String number) {
+        for (int i = 0; i < number.length(); i++) {
+            if (!Character.isDigit(number.charAt(i))) {
+                throw new IllegalArgumentException("등록된 구분자가 아닙니다.");
+            }
+        }
+    }
+}
diff --git a/src/main/java/calculator/util/Constants.java b/src/main/java/calculator/util/Constants.java
new file mode 100644
index 000000000..b47145240
--- /dev/null
+++ b/src/main/java/calculator/util/Constants.java
@@ -0,0 +1,11 @@
+package calculator.util;
+
+import java.util.List;
+
+public class Constants {
+    public static final String CUSTOM_PREFIX = "//";
+    public static final String CUSTOM_SUFFIX = "\\n";
+    public static final int SEPARATOR_LENGTH = 1;
+    public static final String DECIMAL_POINT = ".";
+    public static final List<String> DEFAULT_SEPARATORS = List.of(":", ",");
+}
diff --git a/src/main/java/calculator/util/SeparatorManager.java b/src/main/java/calculator/util/SeparatorManager.java
new file mode 100644
index 000000000..cfba21158
--- /dev/null
+++ b/src/main/java/calculator/util/SeparatorManager.java
@@ -0,0 +1,29 @@
+package calculator.util;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+public class SeparatorManager {
+    List<String> separators;
+
+    public SeparatorManager() {
+        this.separators = new ArrayList<>(Constants.DEFAULT_SEPARATORS);
+    }
+
+    private boolean exists(String separator) {
+        return separators.contains(separator);
+    }
+
+    public void add(String separator) {
+        if (this.exists(separator)) {
+            throw new IllegalArgumentException("이미 존재하는 구분자입니다.");
+        }
+        separators.add(separator);
+    }
+
+    public List<String> getSeparators() {
+        return Collections.unmodifiableList(separators);
+    }
+}
diff --git a/src/main/java/calculator/util/StringHandler.java b/src/main/java/calculator/util/StringHandler.java
new file mode 100644
index 000000000..a752cc753
--- /dev/null
+++ b/src/main/java/calculator/util/StringHandler.java
@@ -0,0 +1,40 @@
+package calculator.util;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class StringHandler {
+    public String extractSeparator(String input) {
+        int start = Constants.CUSTOM_PREFIX.length() ;
+        int end = input.indexOf(Constants.CUSTOM_SUFFIX);
+        return input.substring(start, end);
+    }
+
+    public List<String> getNumbers(List<String> separators, String input) {
+        List<String> splitInput = new ArrayList<>();
+        splitInput.add(input);
+
+        for (String separator : separators) {
+            splitInput = splitBySeparator(splitInput, separator);
+        }
+
+        return splitInput;
+    }
+
+    private List<String> splitBySeparator(List<String> inputList, String separator) {
+        List<String> result = new ArrayList<>();
+
+        for (String part : inputList) {
+            String[] splitParts = part.split(separator);
+            result.addAll(Arrays.asList(splitParts));
+        }
+
+        return result;
+    }
+
+    public String removeCustom(String input) {
+        int numberIndex = input.indexOf(Constants.CUSTOM_SUFFIX) + 2;
+        return input.substring(numberIndex);
+    }
+}
diff --git a/src/main/java/calculator/util/Validator.java b/src/main/java/calculator/util/Validator.java
new file mode 100644
index 000000000..e25736cfc
--- /dev/null
+++ b/src/main/java/calculator/util/Validator.java
@@ -0,0 +1,48 @@
+package calculator.util;
+
+public class Validator {
+    public boolean hasCustomSeparator(String input) {
+        if (isEmpty(input)) {
+            return false;
+        }
+        return input.startsWith(Constants.CUSTOM_PREFIX) && input.contains(Constants.CUSTOM_SUFFIX);
+    }
+
+    public boolean isStartWithDigit(String input) {
+        if (isEmpty(input)) {
+            return false;
+        }
+        return Character.isDigit(input.charAt(0));
+    }
+
+    public boolean isEmpty(String input) {
+        return input == null || input.isBlank();
+    }
+
+    public void validateSeparator(String separator) {
+        if (separator.length() != Constants.SEPARATOR_LENGTH) {
+            throw new IllegalArgumentException("구분자의 길이는 1이어야 합니다.");
+        }
+        if (separator.equals(Constants.DECIMAL_POINT)) {
+            throw new IllegalArgumentException(".은 구분자가 될 수 없습니다.");
+        }
+        if (isStartWithDigit(separator)) {
+            throw new IllegalArgumentException("숫자는 구분자가 될 수 없습니다.");
+        }
+    }
+
+    public void validateInput(String input) {
+        if (isEmpty(input)) {
+            return;
+        }
+        if (hasCustomSeparator(input)) {
+            return;
+        }
+        if (isStartWithDigit(input)) {
+            if ((!input.contains(Constants.CUSTOM_PREFIX) && !input.contains(Constants.CUSTOM_SUFFIX))) {
+                return;
+            }
+        }
+        throw new IllegalArgumentException("포멧에 맞게 입력해 주세요.(ex://@\\n1@2:3,4)");
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/calculator/AdderTest.java b/src/test/java/calculator/AdderTest.java
new file mode 100644
index 000000000..b62ab4c9e
--- /dev/null
+++ b/src/test/java/calculator/AdderTest.java
@@ -0,0 +1,24 @@
+package calculator;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import calculator.util.Adder;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+class AdderTest {
+    Adder adder = new Adder();
+
+    @Test
+    void 공백일때_0을_return_하는지() {
+        adder.add(List.of(""));
+        assertEquals(0, adder.getAnswer());
+    }
+
+    @Test
+    void 오버플로우_발생시_예외_처리() {
+        assertThatThrownBy(() ->adder.add(List.of(String.valueOf(Double.MAX_VALUE),"1")))
+                .isInstanceOf(IllegalArgumentException.class);
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/calculator/ApplicationTest.java b/src/test/java/calculator/ApplicationTest.java
index 93771fb01..0d174ce87 100644
--- a/src/test/java/calculator/ApplicationTest.java
+++ b/src/test/java/calculator/ApplicationTest.java
@@ -16,6 +16,14 @@ class ApplicationTest extends NsTest {
         });
     }
 
+    @Test
+    void 공백_입력() {
+        assertSimpleTest(() -> {
+            run(" ");
+            assertThat(output()).contains("결과 : 0");
+        });
+    }
+
     @Test
     void 예외_테스트() {
         assertSimpleTest(() ->
diff --git a/src/test/java/calculator/SeparatorManagerTest.java b/src/test/java/calculator/SeparatorManagerTest.java
new file mode 100644
index 000000000..5335bd1a0
--- /dev/null
+++ b/src/test/java/calculator/SeparatorManagerTest.java
@@ -0,0 +1,29 @@
+package calculator;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThatCode;
+
+import calculator.util.SeparatorManager;
+import org.junit.jupiter.api.Test;
+
+class SeparatorManagerTest {
+    SeparatorManager separatorManager = new SeparatorManager();
+
+    @Test
+    void 이미_있는_구분자라면_예외_처리() {
+        assertThatThrownBy(() -> separatorManager.add(":"))
+                .isInstanceOf(IllegalArgumentException.class);
+    }
+
+    @Test
+    void 없는_구분자라면_정상_작동() {
+        assertThatCode(() -> separatorManager.add(";"))
+                .doesNotThrowAnyException();
+    }
+
+    @Test
+    void 받은_구분자_리스트의_수정_불가한지_확인() {
+        assertThatThrownBy(() -> separatorManager.getSeparators().remove(0))
+                .isInstanceOf(UnsupportedOperationException.class);
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/calculator/StringHandlerTest.java b/src/test/java/calculator/StringHandlerTest.java
new file mode 100644
index 000000000..6b903435f
--- /dev/null
+++ b/src/test/java/calculator/StringHandlerTest.java
@@ -0,0 +1,38 @@
+package calculator;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import calculator.util.SeparatorManager;
+import calculator.util.StringHandler;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+class StringHandlerTest {
+    StringHandler handler = new StringHandler();
+    SeparatorManager separatorManager = new SeparatorManager();
+
+    @Test
+    void 커스텀구분자만_리턴하는지_확인() {
+        assertEquals("@",
+                handler.extractSeparator("//@\\n1@2@3"));
+    }
+
+
+    @Test
+    void 숫자만_반환하는지_확인() {
+        assertEquals(List.of("1", "2", "3"),
+                handler.getNumbers(separatorManager.getSeparators(), "1:2,3"));
+    }
+
+    @Test
+    void 두자리_이상의_숫자가_잘_반환_되는지_확인() {
+        assertEquals(List.of("12", "36", "222"),
+                handler.getNumbers(separatorManager.getSeparators(), "12,36:222"));
+    }
+
+    @Test
+    void 커스텀_구분자_선언부분만_잘라내는지_확인() {
+        assertEquals("1,2;3",
+                handler.removeCustom("//;\\n1,2;3"));
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/calculator/ValidatorTest.java b/src/test/java/calculator/ValidatorTest.java
new file mode 100644
index 000000000..20c2718db
--- /dev/null
+++ b/src/test/java/calculator/ValidatorTest.java
@@ -0,0 +1,50 @@
+package calculator;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import calculator.util.Validator;
+import org.junit.jupiter.api.Test;
+
+class ValidatorTest {
+    Validator validator = new Validator();
+
+    @Test
+    void 커스텀_구분자의_포맷이_올바르면_True_반환() {
+        assertTrue(validator.hasCustomSeparator("//;\\n1;2;3"));
+    }
+
+    @Test
+    void 커스텀_구분자가_없다면_False_반환() {
+        assertFalse(validator.hasCustomSeparator("1:2:3"));
+    }
+
+    @Test
+    void 숫자로_시작한다면_True_반환() {
+        assertTrue(validator.isStartWithDigit("1;2;3"));
+    }
+
+    @Test
+    void 숫자로_시작하지_않으면_False_반환() {
+        assertFalse(validator.isStartWithDigit("//;\\n"));
+    }
+
+    @Test
+    void 올바른_포맷일때_아무_처리도_하지_않음() {
+        String[] testCases = {"//@\\n1@2@3", " ", "", "//@\\n", "1:2:3"};
+        for (String testCase : testCases) {
+            assertDoesNotThrow(() -> validator.validateInput(testCase));
+        }
+    }
+
+    @Test
+    void 잘못된_포맷은_예외_발생() {
+        String[] testCases = {"1@2@3//@\n", "\n@//1,2,3", "abc"};
+        for (String testCase : testCases) {
+            assertThatThrownBy(() -> validator.validateInput(testCase))
+                    .isInstanceOf(IllegalArgumentException.class);
+        }
+    }
+}
\ No newline at end of file