diff --git a/src/main/java/Baseball.java b/src/main/java/Baseball.java
new file mode 100644
index 0000000..c5a1a9f
--- /dev/null
+++ b/src/main/java/Baseball.java
@@ -0,0 +1,20 @@
+public class Baseball {
+    private String comNumber;
+    private String userNumber;
+
+    public String getComNumber() {
+        return comNumber;
+    }
+
+    public void setComNumber(String comNumber) {
+        this.comNumber = comNumber;
+    }
+
+    public String getUserNumber() {
+        return userNumber;
+    }
+
+    public void setUserNumber(String userNumber) {
+        this.userNumber = userNumber;
+    }
+}
diff --git a/src/main/java/BaseballServiceImpl.java b/src/main/java/BaseballServiceImpl.java
new file mode 100644
index 0000000..790b791
--- /dev/null
+++ b/src/main/java/BaseballServiceImpl.java
@@ -0,0 +1,92 @@
+public class BaseballServiceImpl implements SportsGameService {
+
+    @Override
+    public String playGame(String userNumber) {
+        Baseball b = new Baseball();
+        b.setComNumber(getRandomInteger(9, 1, 3));
+        b.setUserNumber(userNumber);
+        System.out.println("상대방 숫자는 " + b.getComNumber() + "입니다.");
+        return checkNumber(b.getUserNumber(), b.getComNumber());
+    }
+
+    private static final Integer NUM_DIGIT = 3;
+    private static final String OVER_DIGIT_MESSAGE = "세자리 수를 입력해주세요.";
+    @Override
+    public Boolean checkLength(String userNumber) {
+        if (userNumber.length() != NUM_DIGIT) {
+            System.out.println(OVER_DIGIT_MESSAGE);
+            return false;
+        }
+        return true;
+    }
+    private static final Integer GAME_QUIT = 000;
+    @Override
+    public Boolean gameQuit(String userNumber) {
+        if (userNumber.equals(GAME_QUIT)) {
+            return false;
+        }
+        return true;
+    }
+
+    private static final String NOT_INT_MESSAGE = "문자는 안됩니다. 숫자를 입력하세요.";
+    @Override
+    public Boolean isInt(String userNumber) {
+        try {
+            Integer.parseInt(userNumber);
+            return true;
+        } catch (NumberFormatException e) {
+            System.out.println(NOT_INT_MESSAGE);
+            return false;
+        }
+
+    }
+
+    private String checkNumber(String userNumber, String comNumber) {
+        int ballCount = 0;
+        int strikeCount = 0;
+        int cn = Integer.parseInt(comNumber);
+        for (int i = 0; i < comNumber.length(); i++) {
+            String kcn = cn % 10 + "";
+            int chk = reverseStr(userNumber).lastIndexOf(kcn);
+            if (chk > -1 && chk != i) {
+                ballCount++;
+            }
+            if (chk == i) {
+                strikeCount++;
+            }
+            cn = cn / 10;
+        }
+        return result(ballCount, strikeCount);
+    }
+
+    private String result(int ballCount, int strikeCount) {
+        String res = "";
+        if (ballCount > 0) {
+            res += ballCount + " ball ";
+        }
+        if (strikeCount > 0) {
+            res += strikeCount + " strike";
+        }
+        if (ballCount == 0 && strikeCount == 0) {
+            res = "nothing";
+        }
+        return res;
+    }
+
+    private String getRandomInteger(int maximum, int minimum, int length) {
+        String res = "";
+        while(!(res.length() == length)) {
+            int num = ((int) (Math.random() * (maximum - minimum))) + minimum;
+            if (res.indexOf(num + "") == -1) {
+                res +=num;
+            }
+        }
+        return res;
+    }
+
+
+    private String reverseStr(String s) {
+        return (new StringBuffer(s)).reverse().toString();
+    }
+}
+
diff --git a/src/main/java/Main.java b/src/main/java/Main.java
new file mode 100644
index 0000000..daa4fc8
--- /dev/null
+++ b/src/main/java/Main.java
@@ -0,0 +1,21 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        SportsGameService baseballGame = new BaseballServiceImpl();
+        System.out.println("1부터 9까지로 이루어진 숫자 3개를 눌러주세요.\n더 이상 게임을 원하지 않을경우 000 을 입력하세요.");
+        while (true) {
+            Scanner sc = new Scanner(System.in);
+            System.out.println("숫자를 입력하세요.");
+            String userNumber = sc.next();
+            if (!baseballGame.gameQuit(userNumber)) {
+                break;
+            }
+            if (!baseballGame.isInt(userNumber) || !baseballGame.checkLength(userNumber)) {
+                continue;
+            }
+            System.out.println(baseballGame.playGame(userNumber));
+        }
+        System.out.println("게임이 종료됐습니다. 감사합니다.");
+    }
+}
diff --git a/src/main/java/SportsGameService.java b/src/main/java/SportsGameService.java
new file mode 100644
index 0000000..fe7688a
--- /dev/null
+++ b/src/main/java/SportsGameService.java
@@ -0,0 +1,7 @@
+public interface SportsGameService {
+//    baseball game 뿐만 아니라 나중에 soccer 등의 확장성으 고려해 service 로 만듦
+    String playGame(String userInput);
+    Boolean gameQuit(String userNumber);
+    Boolean isInt(String userNumber);
+    Boolean checkLength(String userNumber);
+}
diff --git a/src/main/java/method1.md b/src/main/java/method1.md
new file mode 100644
index 0000000..e69de29