diff --git a/src/main/java/Cacluate.java b/src/main/java/Cacluate.java
index 943e575..fc456c8 100644
--- a/src/main/java/Cacluate.java
+++ b/src/main/java/Cacluate.java
@@ -1,8 +1,6 @@
 public class Cacluate {
 
-    private static int result;
-
-    public static int calculate(int first_num, String operator, int second_num){
+    public int calculate(int first_num, String operator, int second_num){
         //연산부
         if (operator == "+") {
             return add(first_num,second_num);
@@ -19,16 +17,16 @@ public static int calculate(int first_num, String operator, int second_num){
         throw new RuntimeException("올바르지 않는 연산자입니다.");
     }
 
-    private static int add(int a,int b){
+    private int add(int a,int b){
         return a+b;
     }
-    private static int sub(int a,int b){
+    private int sub(int a,int b){
         return a-b;
     }
-    private static int mul(int a,int b){
+    private int mul(int a,int b){
         return a*b;
     }
-    private static int div(int a,int b){
+    private int div(int a,int b){
         return a/b;
     }
 
diff --git a/src/main/java/Input.java b/src/main/java/Input.java
index 546178f..2e65df4 100644
--- a/src/main/java/Input.java
+++ b/src/main/java/Input.java
@@ -1,8 +1,8 @@
 import java.util.Scanner;
 
-public class Input {
+class Input {
 
-    public static String[] input(){
+    public String[] input(){
         Scanner scan = new Scanner(System.in);
         String value = scan.nextLine();
         String[] values = value.split(" ");
diff --git a/src/main/java/Main.java b/src/main/java/Main.java
index 22dcf08..df889f1 100644
--- a/src/main/java/Main.java
+++ b/src/main/java/Main.java
@@ -1,8 +1,11 @@
 public class Main {
     public static void main(String[] args) {
 
-        String[] values = Input.input();
-        int result = Preprocessing.classify(values);
+        Input i1 = new Input();
+        String[] values = i1.input();
+
+        Preprocessing pre = new Preprocessing();
+        int result = pre.classify(values);
         //결과값 출력
         System.out.println(result);
     }
diff --git a/src/main/java/Preprocessing.java b/src/main/java/Preprocessing.java
index 18b06f1..1ff6359 100644
--- a/src/main/java/Preprocessing.java
+++ b/src/main/java/Preprocessing.java
@@ -1,4 +1,4 @@
-public class Preprocessing {
+class Preprocessing {
 
     private static int first_num = 0;
     private static int second_num = 0;
@@ -6,7 +6,7 @@ public class Preprocessing {
     public static String operator = "";
 
     //숫자 or 연산자 or 에러(숫자x, 연산자x)?
-    private static boolean isNumber(String a) {
+    private boolean isNumber(String a) {
         //잠결에 해서 어떻게 했는지 설명못하겠어 무의식속에서 코드가 완성됐어
         boolean isNum;
         isNum = true;
@@ -23,7 +23,7 @@ private static boolean isNumber(String a) {
     }
 
     //연산자 부여
-    public static void setOper(String oper) {
+    public void setOper(String oper) {
         if (oper.equals("+")) {
             operator = "+";
         }
@@ -40,17 +40,18 @@ public static void setOper(String oper) {
     }
 
     //숫자 부여
-    public static void setNumber(int idx, String num) {
+    public void setNumber(int idx, String num) {
         if (idx == 0) { //제일 처음일때만
             return_num = Integer.parseInt(num);
         } else { // 두번째 숫자 들어올때
             first_num = return_num;
             second_num = Integer.parseInt(num);
-            return_num = Cacluate.calculate(first_num, operator, second_num);
+            Cacluate cal = new Cacluate();
+            return_num = cal.calculate(first_num, operator, second_num);
         }
     }
 
-    public static int classify(String[] values) {
+    public int classify(String[] values) {
         //잘못된 연산식인지 먼저 확인.
         wrongMath(values);
 
@@ -65,7 +66,7 @@ public static int classify(String[] values) {
         return return_num;
     }//end classify()
 
-    private static void wrongMath(String[] values) {
+    private void wrongMath(String[] values) {
         if (values.length % 2 == 0)
             throw new IllegalArgumentException("잘못된 연산입니다. 다시 입력하세요.");
     }
diff --git a/src/test/java/test.java b/src/test/java/test.java
index 58e0465..76f53f9 100644
--- a/src/test/java/test.java
+++ b/src/test/java/test.java
@@ -15,8 +15,8 @@ public class test {
     public void successTest() throws Exception {
         String value = "5 + 3 * 4 / 2";
         String[] values = value.split(" ");
-
-        assertThat(Preprocessing.classify(values)).isEqualTo(16);
+        Preprocessing pretest = new Preprocessing();
+        assertThat(pretest.classify(values)).isEqualTo(16);
     }
 
 
@@ -26,9 +26,9 @@ public void validationTest() {
         String errorValue = "2 + 3 * 4 / ";
 
         String[] errorValues = errorValue.split(" ");
-
+        Preprocessing pretest = new Preprocessing();
         assertThatThrownBy(() -> {
-            Preprocessing.classify(errorValues);
+            pretest.classify(errorValues);
         }).isInstanceOf(IllegalArgumentException.class)
                 .hasMessageContaining("잘못된 연산입니다. 다시 입력하세요.");
 
@@ -38,16 +38,14 @@ public void validationTest() {
     @Test
     @DisplayName("에러_잘못된_연산자")
     public void wrong_input_value() {
-
         String errorValue = "2 + 3 _ 4";
         String[] errorValues = errorValue.split(" ");
+        Preprocessing pretest = new Preprocessing();
         assertThatThrownBy(() -> {
-            Preprocessing.classify(errorValues);
+            pretest.classify(errorValues);
         }).isInstanceOf(RuntimeException.class)
                 .hasMessageContaining("올바르지 않는 연산자입니다.");
     }
 
 
-
-
 }