diff --git a/README.md b/README.md
index 8d7e8aee..18801bd8 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,25 @@
-# java-baseball-precourse
\ No newline at end of file
+## 구현 기능
+
+### BaseBallApplication
+
+- 숫자 야구 시작 기능
+
+### MajorLeague
+
+- 야구 게임의 전반적인 흐름 제어 기능
+
+### AutomaticBallStrikeSystem
+
+- 볼(Strike/Ball) 판독 기능
+
+### RandomBall
+
+- 컴퓨터의 랜덤 공 생성 기능
+
+### Result
+
+- 판독된 볼의 리턴을 담당하는 클래스
+
+### ValidBall
+
+- 사용자로부터 입력받은 숫자가 유효한지 확인하는 기능
diff --git a/src/main/java/AutomaticBallStrikeSystem.java b/src/main/java/AutomaticBallStrikeSystem.java
new file mode 100644
index 00000000..1bc4e632
--- /dev/null
+++ b/src/main/java/AutomaticBallStrikeSystem.java
@@ -0,0 +1,45 @@
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+
+public class AutomaticBallStrikeSystem {
+
+    public Result determine(int number, int answer) {
+        int strikeCount = determineStrike(number, answer);
+        int ballCount = determineBall(number, answer);
+        return new Result(strikeCount, ballCount);
+    }
+
+    private int determineStrike(int number, int answer) {
+        int strike = 0;
+        while (number > 0) {
+            Integer unitsOfNumber = number % 10;
+            Integer unitsOfAnswer = answer % 10;
+            if (unitsOfNumber == unitsOfAnswer) {
+                strike += 1;
+            }
+            number /= 10;
+            answer /= 10;
+        }
+        return strike;
+    }
+
+    private int determineBall(Integer number, Integer answer) {
+        int ball = 0;
+        String numToStr = number.toString();
+        String ansToStr = answer.toString();
+
+        for (int i = 0; i < numToStr.length(); i++) {
+            char numChar = numToStr.charAt(i);
+            for (int j = 0; j < ansToStr.length(); j++) {
+                char ansChar = ansToStr.charAt(j);
+                if (i != j && numChar == ansChar) {
+                    ball += 1;
+                }
+            }
+        }
+        return ball;
+    }
+}
+
diff --git a/src/main/java/BaseBallApplication.java b/src/main/java/BaseBallApplication.java
new file mode 100644
index 00000000..48f94408
--- /dev/null
+++ b/src/main/java/BaseBallApplication.java
@@ -0,0 +1,15 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Scanner;
+
+public class BaseBallApplication {
+
+    public static void main(String[] args) throws IOException {
+        do {
+            if (!MajorLeague.playBaseball()) {
+                break;
+            }
+        } while (true);
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/MajorLeague.java b/src/main/java/MajorLeague.java
new file mode 100644
index 00000000..3ee17ed5
--- /dev/null
+++ b/src/main/java/MajorLeague.java
@@ -0,0 +1,69 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+public class MajorLeague {
+
+    static boolean playBaseball() throws IOException {
+
+        AutomaticBallStrikeSystem ABS = new AutomaticBallStrikeSystem();
+        RandomBall random = new RandomBall();
+        ValidBall validBall = new ValidBall();
+        int number = random.makeRandomBall();
+
+        while (true) {
+
+            System.out.println("숫자를 입력해 주세요 :");
+            Integer answer = getUserInput();
+            validBall.validate(answer);
+
+            Result result = ABS.determine(number, answer);
+
+            int ballCount = result.getBallCount();
+            int strikeCount = result.getStrikeCount();
+            referee(ballCount, strikeCount);
+        }
+    }
+
+    private static void referee(int ballCount, int strikeCount) throws IOException {
+        if ((ballCount == 0) && (strikeCount == 0)) {
+            System.out.println("낫싱");
+        } else if ((ballCount != 0) && (strikeCount != 0)) {
+            System.out.println("결과: " + ballCount + "볼, " + strikeCount + "스트라이크");
+        }
+        else if (strikeCount == 3) {
+            decideGameEnd();
+        }
+    }
+
+    private static boolean decideGameEnd() throws IOException {
+        System.out.println("3개의 숫자를 모두 맞히셨습니다! 게임 종료");
+        System.out.println("게임을 새로 시작하려면 1, 종료하려면 2를 입력하세요.");
+
+        Integer answer = getUserInput();
+        if (answer == 1) {
+            MajorLeague.playBaseball();
+        }
+        if (answer == 2) {
+            return false;
+        }
+        handleInvalidInput();
+        return decideGameEnd();
+    }
+
+
+    private static Integer getUserInput() throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        Integer answer = Integer.parseInt(br.readLine());
+        return answer;
+    }
+
+
+    private static void handleInvalidInput() {
+        System.out.println("잘못된 입력입니다. 다시 시도하세요.");
+    }
+
+}
\ No newline at end of file
diff --git a/src/main/java/RandomBall.java b/src/main/java/RandomBall.java
new file mode 100644
index 00000000..1d307df5
--- /dev/null
+++ b/src/main/java/RandomBall.java
@@ -0,0 +1,25 @@
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class RandomBall {
+
+    public int makeRandomBall() {
+        List<Integer> numbers = new ArrayList<>();
+
+        for (int i = 1; i <= 9; i++) {
+            numbers.add(i);
+        }
+
+        Collections.shuffle(numbers);
+        StringBuilder randomNumberBuilder = new StringBuilder();
+
+        for (int i = 0; i < 3; i++) {
+            randomNumberBuilder.append(numbers.get(i));
+        }
+
+        int randomNumber = Integer.parseInt(randomNumberBuilder.toString());
+
+        return randomNumber;
+    }
+}
diff --git a/src/main/java/Result.java b/src/main/java/Result.java
new file mode 100644
index 00000000..806bfdd6
--- /dev/null
+++ b/src/main/java/Result.java
@@ -0,0 +1,17 @@
+public class Result {
+    private Integer strikeCount;
+    private Integer ballCount;
+
+    public Result(Integer strikeCount, Integer ballCount) {
+        this.strikeCount = strikeCount;
+        this.ballCount = ballCount;
+    }
+
+    public Integer getStrikeCount() {
+        return strikeCount;
+    }
+
+    public Integer getBallCount() {
+        return ballCount;
+    }
+}
diff --git a/src/main/java/ValidBall.java b/src/main/java/ValidBall.java
new file mode 100644
index 00000000..f2577805
--- /dev/null
+++ b/src/main/java/ValidBall.java
@@ -0,0 +1,26 @@
+import java.util.HashSet;
+
+public class ValidBall {
+
+    public void validate(int answer) {
+        validateRange(answer);
+        validateDuplication(answer);
+    }
+
+    private void validateDuplication(int answer) {
+        HashSet<Integer> set = new HashSet<>();
+        while (answer > 0) {
+            int digit = answer % 10;
+            if (!set.add(digit)) {
+                throw new IllegalArgumentException("입력된 숫자 중 중복되는 숫자가 있습니다.");
+            }
+            answer /= 10;
+        }
+    }
+
+    private void validateRange(int number) {
+        if ((number < 111) || (number > 999)) {
+            throw new IllegalArgumentException("잘못된 범위의 입력입니다");
+        }
+    }
+}