diff --git a/docs/README.md b/docs/README.md
index e69de29..cdd5615 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -0,0 +1,65 @@
+## Player 클래스 (사용자로 부터 숫자를 입력받음)
+### 기능
+- `guess()`: 사용자 입력을 받아 숫자 리스트로 반환 
+
+## AiPlayer 클래스 (상대방)
+### 기능
+- `correct()` :랜덤한 3자리의 숫자를 반환
+- `checkBallsAndStrikes()` : 입력받은 사용자의 숫자에 대해 결과를 볼,스트라이크,낫싱으로 결과값 반환
+
+### 상태값
+- `ballcounting : BallCounting`
+- `strike : String`
+- `ball : String`
+- `nothing : String`
+
+## GameHost 클래스
+### 기능 
+- `baseballGame()` : 게임 시작 문구를 출력합니다
+- `end()` : 3스트라이크 시 게임 종료 문구를 출력합니다
+- `askRestart()` : 1입력시 종료, 2 입력 시 재시작을 합니다
+
+## BallCounting 클래스
+### 기능
+- `setCorrect` : aiPlayer가 출력한 값을 가져옵니다
+- `setGuess` : 사용자가 예측한 숫자를 가져옵니다
+- `getStrike()` : 같은 자리의 숫자가 일치할 시 해당 횟수에 따라 스트라이크를 출력합니다
+- `getBall()` : 다른 자리의 숫자가 일치할 시 해당 횟수에 따라 볼을 출력합니다
+- `getNothing()` : 같은 숫자가 전혀 없을 시 낫싱을 출력합니다
+
+### 상태값
+- `guess : List<Integer> `
+- `correct : List<Integer> `
+
+## BaseballGame 클래스
+### 기능
+- `runGame()` : 게임을 진행합니다
+
+### 상태값
+- `gameHost : GameHost`
+- `aiPlayer : AiPlayer`
+- `ballCounting :BallCounting`
+- `player : Player`
+
+## ExceptionMessage
+### 기능
+- `checkInputLength` : player 입력 숫자가 3자리에 대한 예외사항
+
+## 리팩토링에 대한 피드백 내용
+- 현재 마크다운 문서는 클래스 중심으로 되어 있음 -> 앞으로는 객체중심으로 작성
+- 클래스와 객체 대한 이해와 공부가 필요함
+- 연관 관계가 과함
+- 필드에 대해서 초기화를 할 때 생성자를 만들어서 초기화 해도 된다
+ex) ``` public AiPlayer(BallCounting ballCounting) {
+    this.ballCounting = ballCounting;
+    } ```
+-> ```  public AiPlayer() {
+        this.ballCounting = new BallCuonting(); 
+    }```
+- 클래스 명은 동사X, 명사 (Play 클래스 = 동사임)
+- 메서드명을 좀 더 명확하게!
+ex) `GameHost`에서 메서드명 `start` -> `printStart`, `end` -> `printEnd`,
+`AiPlayer`에서 `correct`-> `pickRandomNumber` 
+- `Setter`는 최대한 사용x
+- static 메서드에 대해서 공부해보고 `BallCounting` 클래스에서 활용 + 필드 선언이 필요x
+- 객체 다이어그램을 그리고 시작하는것도 좋음
diff --git a/src/main/java/baseball/AiPlayer.java b/src/main/java/baseball/AiPlayer.java
new file mode 100644
index 0000000..46f6f1b
--- /dev/null
+++ b/src/main/java/baseball/AiPlayer.java
@@ -0,0 +1,49 @@
+package baseball;
+
+import camp.nextstep.edu.missionutils.Randoms;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class AiPlayer {
+
+    private final BallCounting ballCounting;
+    private String strike;
+    private String ball;
+    private String nothing;
+
+    public AiPlayer(BallCounting ballCounting) {
+        this.ballCounting = ballCounting;
+    }
+
+    public List<Integer> correct() {
+
+        List<Integer> computer = new ArrayList<>();
+        while (computer.size() < 3) {
+            int randomNumber = Randoms.pickNumberInRange(1, 9);
+            if (!computer.contains(randomNumber)) {
+                computer.add(randomNumber);
+            }
+        }
+        return computer;
+    }
+
+    public String checkBallsAndStrikes(List<Integer> correct,List<Integer> guess){
+        List<Integer> numberOfStrike = ballCounting.getStrike(correct,guess);
+        List<Integer> numberOfBall = ballCounting.getBall(correct,guess);
+        strike ="";
+        ball = "";
+        nothing ="";
+
+        if(numberOfStrike.size()>0){
+            strike = numberOfStrike.size() + "스트라이크";
+        }
+        if(numberOfBall.size() >0) {
+            ball = numberOfBall.size() + "볼";
+        }
+        if(numberOfStrike.size() == 0 && numberOfBall.size() == 0){
+            nothing = ballCounting.getNothing();
+        }
+        return ball + " " + strike + nothing;
+    }
+}
diff --git a/src/main/java/baseball/Application.java b/src/main/java/baseball/Application.java
index 8d761b8..73572c1 100644
--- a/src/main/java/baseball/Application.java
+++ b/src/main/java/baseball/Application.java
@@ -3,10 +3,7 @@
 public class Application {
 
     public static void main(String[] args) {
-
         Start start = new Start();
-        start.button();
+        start.runGame();
     }
-
-
 }
diff --git a/src/main/java/baseball/BallCount.java b/src/main/java/baseball/BallCount.java
deleted file mode 100644
index bf66d7b..0000000
--- a/src/main/java/baseball/BallCount.java
+++ /dev/null
@@ -1,52 +0,0 @@
-package baseball;
-
-import java.util.ArrayList;
-import java.util.List;
-
-public class BallCount {
-
-    private List<Integer> correct;
-    private List<Integer> guess;
-
-    public void setCorrect(List<Integer> correct) {
-        this.correct = correct;
-    }
-
-    public void setGuess(List<Integer> guess) {
-        this.guess = guess;
-    }
-
-    public List<Integer> getCorrect() {
-        return correct;
-    }
-
-    public List<Integer> getGuess() {
-        return guess;
-    }
-
-    public List<Integer> strike() {
-        List<Integer> sameNumber = new ArrayList<>();
-        for(int i = 0; i <3; i++) {
-           if(getCorrect().get(i) == getGuess().get(i)){
-               sameNumber.add(getCorrect().get(i));
-            }
-        }return sameNumber;
-    }
-
-    public List<Integer> ball() {
-        List<Integer> common = new ArrayList<>(equalsNumber());
-        common.removeAll(strike());
-
-        return common;
-    }
-
-    public List<Integer> equalsNumber() {
-        List<Integer> common = new ArrayList<>(getGuess());
-        common .retainAll(getCorrect());
-
-        return common ;
-    }
-}
-
-
-
diff --git a/src/main/java/baseball/BallCounting.java b/src/main/java/baseball/BallCounting.java
new file mode 100644
index 0000000..2a1664d
--- /dev/null
+++ b/src/main/java/baseball/BallCounting.java
@@ -0,0 +1,40 @@
+package baseball;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class BallCounting {
+
+    private List<Integer> correct;
+    private List<Integer> guess;
+
+    public void setCorrect(List<Integer> correct) {
+        this.correct = correct;
+    }
+    public void setGuess(List<Integer> guess) {
+        this.guess = guess;
+    }
+
+    public List<Integer> getStrike(List<Integer> correct,List<Integer> guess) {
+        List<Integer> sameNumber = new ArrayList<>();
+        for(int i = 0; i <3; i++) {
+           if(correct.get(i).equals(guess.get(i)) ){
+               sameNumber.add(guess.get(i));
+            }
+        }return sameNumber;
+    }
+
+    public List<Integer> getBall(List<Integer> correct,List<Integer> guess) {
+        List<Integer> common = new ArrayList<>(correct);
+        common.retainAll(guess);
+        common.removeAll(getStrike(correct,guess));
+        return common;
+    }
+
+    public String getNothing() {
+            return "낫싱";
+    }
+}
+
+
+
diff --git a/src/main/java/baseball/Computer.java b/src/main/java/baseball/Computer.java
deleted file mode 100644
index e59e1a0..0000000
--- a/src/main/java/baseball/Computer.java
+++ /dev/null
@@ -1,37 +0,0 @@
-package baseball;
-
-import camp.nextstep.edu.missionutils.Console;
-import camp.nextstep.edu.missionutils.Randoms;
-
-import java.util.ArrayList;
-import java.util.List;
-
-public class Computer {
-
-    public List<Integer> correct() {
-        List<Integer> computer = new ArrayList<>();
-        while (computer.size() < 3) {
-            int randomNumber = Randoms.pickNumberInRange(1, 9);
-            if (!computer.contains(randomNumber)) {
-                computer.add(randomNumber);
-            }
-        }
-        return computer;
-    }
-
-    public void start() {
-        System.out.println("숫자 야구 게임을 시작합니다");
-    }
-
-    public void end() {
-        System.out.println("3개의 숫자를 모두 맞히셨습니다! 게임 종료");
-    }
-
-    public int askRestart() {
-        System.out.println("게임을 새로 시작하려면 1, 종료하려면 2를 입력하세요");
-        return Integer.parseInt(Console.readLine());
-    }
-
-
-
-}
diff --git a/src/main/java/baseball/ExceptionMessage.java b/src/main/java/baseball/ExceptionMessage.java
index a8bd2fd..b35b06d 100644
--- a/src/main/java/baseball/ExceptionMessage.java
+++ b/src/main/java/baseball/ExceptionMessage.java
@@ -4,7 +4,7 @@ public class ExceptionMessage {
 
     public void checkInputLength(String[] input) {
         if (input.length != 3) {
-            throw new InputException("3자리 숫자를 입력하셔야됩니다");
+            throw new IllegalArgumentException("3자리 숫자를 입력하셔야됩니다");
         }
     }
 }
diff --git a/src/main/java/baseball/GameHost.java b/src/main/java/baseball/GameHost.java
new file mode 100644
index 0000000..dbf814d
--- /dev/null
+++ b/src/main/java/baseball/GameHost.java
@@ -0,0 +1,23 @@
+package baseball;
+
+import camp.nextstep.edu.missionutils.Console;
+
+public class GameHost {
+
+    public void start() {
+        System.out.println("숫자 야구 게임을 시작합니다");
+    }
+
+    public void end() {
+        System.out.println("3개의 숫자를 모두 맞히셨습니다! 게임 종료");
+    }
+
+    public String askRestart() {
+        Start start = new Start();
+        System.out.println("게임을 새로 시작하려면 1, 종료하려면 2를 입력하세요");
+        int ask = Integer.parseInt(Console.readLine());
+        if (ask == 1){
+            start.runGame();
+        } return "";
+    }
+}
diff --git a/src/main/java/baseball/InputException.java b/src/main/java/baseball/InputException.java
deleted file mode 100644
index 84931eb..0000000
--- a/src/main/java/baseball/InputException.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package baseball;
-
-public class InputException extends IllegalArgumentException {
-
-    public InputException(String message) {
-        super(message);
-    }
-}
diff --git a/src/main/java/baseball/Judgement.java b/src/main/java/baseball/Judgement.java
deleted file mode 100644
index 9adc8f1..0000000
--- a/src/main/java/baseball/Judgement.java
+++ /dev/null
@@ -1,38 +0,0 @@
-package baseball;
-
-public class Judgement {
-
-    private BallCount ballCount;
-
-    public Judgement(BallCount ballCount) {
-
-        this.ballCount = ballCount;
-    }
-
-    public String result() {
-       int strike = ballCount.strike().size();
-       int ball = ballCount.ball().size();
-       int nothing = ballCount.equalsNumber().size();
-
-       return countBall(ball) + countStrike(strike)+ isNothing(nothing);
-    }
-
-    public String countStrike(int strike) {
-        if(strike > 0){
-            return " "+strike +"스트라이크";
-        }return "";
-    }
-
-    public String countBall(int ball) {
-            if (ball > 0) {
-                return  ball + "볼";
-            }return "";
-        }
-
-    public String isNothing(int nothing) {
-        if( nothing == 0) {
-            return "낫싱";
-        }return "";
-    }
-
-}
diff --git a/src/main/java/baseball/Player.java b/src/main/java/baseball/Player.java
index 073edbc..4f1db05 100644
--- a/src/main/java/baseball/Player.java
+++ b/src/main/java/baseball/Player.java
@@ -20,5 +20,4 @@ public List<Integer> guess() {
         }
         return user;
     }
-
 }
diff --git a/src/main/java/baseball/Start.java b/src/main/java/baseball/Start.java
index 07ffe6d..c619dea 100644
--- a/src/main/java/baseball/Start.java
+++ b/src/main/java/baseball/Start.java
@@ -4,38 +4,33 @@
 
 public class Start {
 
-    private final Computer computer;
-    private final BallCount ballCount;
-    private Player player;
-    private Judgement judgement;
+    private final GameHost gameHost;
+    private final AiPlayer aiPlayer;
+    private final BallCounting ballCounting;
+    private final Player player;
 
     public Start() {
-        this.computer = new Computer();
+        this.gameHost = new GameHost();
+        this.ballCounting = new BallCounting();
+        this.aiPlayer = new AiPlayer(ballCounting);
         this.player = new Player();
-        this.ballCount = new BallCount();
-        this.judgement = new Judgement(ballCount);
     }
 
-    public void button() {
-        computer.start();
-        List<Integer> correct = computer.correct();
-        ballCount.setCorrect(correct);
+    public void runGame() {
+        gameHost.start();
+        List<Integer> correct = aiPlayer.correct();
+        ballCounting.setCorrect(correct);
         while (true) {
             List<Integer> guess = player.guess();
-            ballCount.setGuess(guess);
+            ballCounting.setGuess(guess);
 
-            System.out.println(judgement.result());
-            if (guess.equals(correct)) break;
+            System.out.println(aiPlayer.checkBallsAndStrikes(correct,guess));
+            if (guess.equals(correct)) {
+                System.out.println("3스트라이크");
+                break;
+            }
         }
-        computer.end();
-        int ask = computer.askRestart();
-        if(ask == 1){
-            restart();
-        }
-    }
-
-    public void restart() {
-        new Start().button();
+        gameHost.end();
+        gameHost.askRestart();
     }
-
 }