diff --git a/src/main/java/Calculator.java b/src/main/java/Calculator.java
new file mode 100644
index 0000000..b96f26c
--- /dev/null
+++ b/src/main/java/Calculator.java
@@ -0,0 +1,62 @@
+import java.util.ArrayList;
+import java.util.List;
+
+public class Calculator {
+    private static final String ADD_OPERATION = "+";
+    private static final String SUBTRACT_OPERATION = "-";
+    private static final String MULTIPLY_OPERATION = "*";
+    private static final String DIVIDE_OPERATION = "/";
+    private static final int NUMBER_INDEX = 0;
+    private static final int OPERATION_INDEX = 1;
+
+    private List<String> numberList = new ArrayList<>();
+    private List<String> operationList = new ArrayList<>();
+    private int result = 0;
+
+    public int operation(int firstNumber, int secondNumber, String operation) {
+        switch (operation) {
+            case ADD_OPERATION:
+                result = firstNumber + secondNumber;
+                break;
+            case SUBTRACT_OPERATION:
+                result = firstNumber - secondNumber;
+                break;
+            case MULTIPLY_OPERATION:
+                result = firstNumber * secondNumber;
+                break;
+            case DIVIDE_OPERATION:
+                result = firstNumber / secondNumber;
+                break;
+            default:
+                throw new RuntimeException("부적합한 연산자가 입력되었습니다.");
+        }
+        return result;
+    }
+
+    public int execute(String[] line) {
+        validation(line);
+        addNumberList(line);
+        addOperationList(line);
+        result = Integer.parseInt(numberList.get(0));
+        for (int i = 0; i < operationList.size(); i++) {
+            result = operation(result, Integer.parseInt(numberList.get(i + 1)), operationList.get(i));
+        }
+        return result;
+    }
+
+    private void validation(String[] formattedInput) {
+        if (formattedInput.length%2 == 0) throw new RuntimeException("올바른 식을 완성해주세요.");
+    }
+
+    private void addNumberList(String[] formattedInput) {
+        for (int i = NUMBER_INDEX; i < formattedInput.length; i += 2) {
+            numberList.add(formattedInput[i]);
+        }
+    }
+
+    private void addOperationList(String[] formattedInput) {
+        for (int i = OPERATION_INDEX; i < formattedInput.length; i += 2) {
+            operationList.add(formattedInput[i]);
+        }
+    }
+}
diff --git a/src/main/java/Input.java b/src/main/java/Input.java
new file mode 100644
index 0000000..8328e6e
--- /dev/null
+++ b/src/main/java/Input.java
@@ -0,0 +1,13 @@
+import java.util.Scanner;
+
+public class Input {
+    private static final String BLANK = " ";
+
+    public static String inputExpression() {
+        Scanner scanner = new Scanner(System.in);
+        return scanner.nextLine();
+    }
+    public static String[] split(String line) {
+        return line.split(BLANK);
+    }
+}
diff --git a/src/main/java/Main.java b/src/main/java/Main.java
new file mode 100644
index 0000000..5431642
--- /dev/null
+++ b/src/main/java/Main.java
@@ -0,0 +1,28 @@
+
+
+public class Main {
+
+    public static void main(String[] args) {
+        runCalculate();
+    }
+
+    public static void runCalculate() {
+        Calculator calculator = new Calculator();
+        String[] lineForCalculate = getFormattedInput();
+        try {
+            Output.printOutput(calculator.execute(lineForCalculate));
+        }
+        catch (Exception e){
+            Output.printOutputError(e);
+            runCalculate();
+        }
+    }
+
+    public static String[] getFormattedInput() {
+        String line = Input.inputExpression();
+        String[] splittedLine = Input.split(line);
+        return splittedLine;
+    }
+
+}
+
diff --git a/src/main/java/Output.java b/src/main/java/Output.java
new file mode 100644
index 0000000..65223af
--- /dev/null
+++ b/src/main/java/Output.java
@@ -0,0 +1,10 @@
+public class Output {
+    public static void printOutput(int result) {
+        System.out.println(result);
+    }
+    public static void printOutputError(Exception e) {
+        System.out.println("출력 에러");
+        e.printStackTrace();
+    }
+
+}
diff --git a/src/main/java/main.java b/src/main/java/main.java
deleted file mode 100644
index 80aa024..0000000
--- a/src/main/java/main.java
+++ /dev/null
@@ -1,51 +0,0 @@
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Scanner;
-
-public class main {
-    private static int calculate(int num1, int num2, String op) {
-        int result = 0;
-        switch (op) {
-            case "+" :
-                result = num1 + num2;
-                break;
-            case "-" :
-                result = num1 - num2;
-                break;
-            case "*" :
-                result = num1 * num2;
-                break;
-            case "/" :
-                result = num1 / num2;
-                break;
-        }
-        return result;
-    }
-
-    private static void calculator(String[] line) {
-        List<String> numList = new ArrayList<>();
-        List<String> opList = new ArrayList<>();
-
-        for (int i=0; i<line.length; i+=2) {
-            numList.add(line[i]);
-        }
-        for (int i=1; i<line.length; i+=2) {
-            opList.add(line[i]);
-        }
-        int result = Integer.parseInt(numList.get(0));
-        for (int i=0; i<opList.size(); i++) {
-            result = calculate(result,Integer.parseInt(numList.get(i+1)),opList.get(i));
-        }
-        System.out.println(result);
-    }
-
-
-    public static void main(String[] args) {
-        Scanner scanner = new Scanner(System.in);
-        String value = scanner.nextLine();
-        String[] values = value.split(" ");
-        calculator(values);
-        scanner.close();
-    }
-
-}