diff --git a/README.md b/README.md
index bd90ef0247..70d2f46ba8 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,12 @@
-# java-calculator-precourse
\ No newline at end of file
+# java-calculator-precourse
+
+## 기능 목록
+
+- [x] 빈 문자열 입력 시 0을 반환한다.
+- [x] 숫자 하나를 문자열로 입력할 경우 해당 숫자를 반환한다.
+- [x] 쉼표(,) 구분자로 두 숫자를 입력할 경우 두 숫자의 합을 반환한다.
+- [x] 쉼표(,) 또는 콜론(:) 구분자로 여러 숫자를 입력할 경우 모든 숫자의 합을 반환한다.
+- [x] 커스텀 구분자를 지정할 수 있다. "//구분자\n" 형식으로 커스텀 구분자를 지정하고, 이후 문자열에서 해당 구분자로 숫자를 분리한다.
+- [x] 음수를 입력할 경우 IllegalArgumentException을 발생시킨다.
+- [x] 사용자로부터 문자열을 입력받는다.
+- [x] 계산 결과를 "결과 : {result}" 형식으로 출력한다.
\ No newline at end of file
diff --git a/src/main/java/calculator/Application.java b/src/main/java/calculator/Application.java
index 573580fb40..c60678eeec 100644
--- a/src/main/java/calculator/Application.java
+++ b/src/main/java/calculator/Application.java
@@ -1,7 +1,15 @@
 package calculator;
 
+import camp.nextstep.edu.missionutils.Console;
+
 public class Application {
     public static void main(String[] args) {
-        // TODO: 프로그램 구현
+        System.out.println("덧셈할 문자열을 입력해 주세요.");
+        String input = Console.readLine();
+
+        StringCalculator calculator = new StringCalculator();
+        int result = calculator.calculate(input);
+
+        System.out.println("결과 : " + result);
     }
 }
diff --git a/src/main/java/calculator/StringCalculator.java b/src/main/java/calculator/StringCalculator.java
new file mode 100644
index 0000000000..8450bc67e2
--- /dev/null
+++ b/src/main/java/calculator/StringCalculator.java
@@ -0,0 +1,48 @@
+package calculator;
+
+public class StringCalculator {
+
+    public int calculate(String input) {
+        if (input == null || input.isEmpty()) {
+            return 0;
+        }
+
+        String delimiter = "[,:]";
+        String numbersString = input;
+
+        if (input.startsWith("//")) {
+            int delimiterEndIndex = input.indexOf("\n");
+            if (delimiterEndIndex == -1) {
+                delimiterEndIndex = input.indexOf("\\n");
+                if (delimiterEndIndex != -1) {
+                    String customDelimiter = input.substring(2, delimiterEndIndex);
+                    delimiter = escapeRegex(customDelimiter);
+                    numbersString = input.substring(delimiterEndIndex + 2);
+                }
+            } else {
+                String customDelimiter = input.substring(2, delimiterEndIndex);
+                delimiter = escapeRegex(customDelimiter);
+                numbersString = input.substring(delimiterEndIndex + 1);
+            }
+        }
+
+        String[] numbers = numbersString.split(delimiter);
+        return sum(numbers);
+    }
+
+    private String escapeRegex(String delimiter) {
+        return delimiter.replaceAll("[\\[\\]{}()*+?.\\\\^$|]", "\\\\$0");
+    }
+
+    private int sum(String[] numbers) {
+        int total = 0;
+        for (String number : numbers) {
+            int value = Integer.parseInt(number);
+            if (value < 0) {
+                throw new IllegalArgumentException();
+            }
+            total += value;
+        }
+        return total;
+    }
+}
diff --git a/src/test/java/calculator/StringCalculatorTest.java b/src/test/java/calculator/StringCalculatorTest.java
new file mode 100644
index 0000000000..c88fa1ee56
--- /dev/null
+++ b/src/test/java/calculator/StringCalculatorTest.java
@@ -0,0 +1,52 @@
+package calculator;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+class StringCalculatorTest {
+
+    @Test
+    void 빈_문자열_입력시_0_반환() {
+        StringCalculator calculator = new StringCalculator();
+        int result = calculator.calculate("");
+        assertThat(result).isEqualTo(0);
+    }
+
+    @Test
+    void 숫자_하나_입력시_해당_숫자_반환() {
+        StringCalculator calculator = new StringCalculator();
+        assertThat(calculator.calculate("1")).isEqualTo(1);
+        assertThat(calculator.calculate("5")).isEqualTo(5);
+    }
+
+    @Test
+    void 쉼표_구분자로_두_숫자_입력시_합_반환() {
+        StringCalculator calculator = new StringCalculator();
+        assertThat(calculator.calculate("1,2")).isEqualTo(3);
+    }
+
+    @Test
+    void 쉼표_또는_콜론_구분자로_여러_숫자_입력시_합_반환() {
+        StringCalculator calculator = new StringCalculator();
+        assertThat(calculator.calculate("1,2,3")).isEqualTo(6);
+        assertThat(calculator.calculate("1:2:3")).isEqualTo(6);
+        assertThat(calculator.calculate("1,2:3")).isEqualTo(6);
+    }
+
+    @Test
+    void 커스텀_구분자_사용() {
+        StringCalculator calculator = new StringCalculator();
+        assertThat(calculator.calculate("//;\n1;2;3")).isEqualTo(6);
+        assertThat(calculator.calculate("//|\n1|2|3")).isEqualTo(6);
+        assertThat(calculator.calculate("//;\n1")).isEqualTo(1);
+    }
+
+    @Test
+    void 음수_입력시_예외_발생() {
+        StringCalculator calculator = new StringCalculator();
+        assertThatThrownBy(() -> calculator.calculate("-1,2,3"))
+                .isInstanceOf(IllegalArgumentException.class);
+    }
+}