diff --git a/src/main/java/com/thread/concurrency/counter/AtomicCounter.java b/src/main/java/com/thread/concurrency/counter/AtomicCounter.java
new file mode 100644
index 0000000..1fdf3bd
--- /dev/null
+++ b/src/main/java/com/thread/concurrency/counter/AtomicCounter.java
@@ -0,0 +1,18 @@
+package com.thread.concurrency.counter;
+
+import org.springframework.stereotype.Component;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+@Component
+public class AtomicCounter implements Counter{
+    private final AtomicInteger count = new AtomicInteger(100);
+    @Override
+    public void add(int value) {
+        count.addAndGet(value);
+    }
+    @Override
+    public int show() {
+        return count.get();
+    }
+}
diff --git a/src/main/java/com/thread/concurrency/counter/CompletableFutureCounter.java b/src/main/java/com/thread/concurrency/counter/CompletableFutureCounter.java
new file mode 100644
index 0000000..00e97bb
--- /dev/null
+++ b/src/main/java/com/thread/concurrency/counter/CompletableFutureCounter.java
@@ -0,0 +1,29 @@
+package com.thread.concurrency.counter;
+
+import org.springframework.stereotype.Component;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+
+@Component
+public class CompletableFutureCounter implements Counter{
+
+    private CompletableFuture<Integer> counter;
+    public CompletableFutureCounter(){
+        this.counter = new CompletableFuture<>();
+        counter.complete(100);
+    }
+    @Override
+    public void add(int value) {
+        synchronized (this){
+            counter = counter.thenApply((c) -> c + value);
+        }
+    }
+    @Override
+    public int show() {
+        try {
+            return counter.get();
+        } catch (InterruptedException | ExecutionException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}
diff --git a/src/main/java/com/thread/concurrency/counter/SynchronizedCounter.java b/src/main/java/com/thread/concurrency/counter/SynchronizedCounter.java
new file mode 100644
index 0000000..aa70b45
--- /dev/null
+++ b/src/main/java/com/thread/concurrency/counter/SynchronizedCounter.java
@@ -0,0 +1,19 @@
+package com.thread.concurrency.counter;
+
+import org.springframework.stereotype.Component;
+
+@Component
+public class SynchronizedCounter implements Counter{
+
+    private int counter = 100;
+
+    @Override
+    public synchronized void add(int value) {
+        counter += value;
+    }
+
+    @Override
+    public synchronized int show() {
+        return counter;
+    }
+}
diff --git a/src/test/java/com/thread/concurrency/AtomicCounterTest.java b/src/test/java/com/thread/concurrency/AtomicCounterTest.java
new file mode 100644
index 0000000..d104356
--- /dev/null
+++ b/src/test/java/com/thread/concurrency/AtomicCounterTest.java
@@ -0,0 +1,49 @@
+package com.thread.concurrency;
+
+import com.thread.concurrency.counter.AtomicCounter;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import java.time.Duration;
+import java.time.LocalTime;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+@SpringBootTest
+public class AtomicCounterTest {
+    private final int counteNumber = 1;
+    private final int totalCount = 5000000;
+    private final int maxThreadNumber = 15;
+    private static final Logger logger = LoggerFactory.getLogger(SynchronizedCounterTest.class);
+    @Autowired
+    AtomicCounter counter;
+
+    @Test
+    @DisplayName("synchronized로 스레드 안전한 카운터로 동시에 여러 더하기 수행하기.")
+    public void 여러_더하기_수행_Executor() throws InterruptedException {
+
+        LocalTime lt1 = LocalTime.now();
+        int initalCount = counter.show();
+
+        ExecutorService service = Executors.newFixedThreadPool(maxThreadNumber);
+        CountDownLatch latch = new CountDownLatch(totalCount);
+        for (int i = 0; i < totalCount; i++) {
+            service.submit(() -> {
+                counter.add(counteNumber);
+                latch.countDown();
+            });
+        }
+        latch.await();
+        int finalCount = counter.show();
+        LocalTime lt2 = LocalTime.now();
+        long dif = Duration.between(lt1, lt2).getNano();
+        logger.info("여러_더하기_수행_Executor 테스트가 걸린 시간 : " + ((float)dif / 1000000) + "ms");
+        Assertions.assertEquals(initalCount + totalCount * counteNumber, finalCount);
+    }
+}
diff --git a/src/test/java/com/thread/concurrency/CompletableFutureCounterTest.java b/src/test/java/com/thread/concurrency/CompletableFutureCounterTest.java
new file mode 100644
index 0000000..3999676
--- /dev/null
+++ b/src/test/java/com/thread/concurrency/CompletableFutureCounterTest.java
@@ -0,0 +1,51 @@
+package com.thread.concurrency;
+
+import com.thread.concurrency.counter.CompletableFutureCounter;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.annotation.Bean;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
+
+import java.time.Duration;
+import java.time.LocalTime;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.*;
+
+@SpringBootTest
+public class CompletableFutureCounterTest {
+
+    private final int counteNumber = 1;
+    private final int totalCount = 5000;
+    private final int maxThreadNumber = 15;
+    private static final Logger logger = LoggerFactory.getLogger(CompletableFutureCounterTest.class);
+
+    @Autowired
+    CompletableFutureCounter counter;
+    @Test
+    @DisplayName("CompletableFuture로 스레드 안전한 카운터로 동시에 여러 더하기 수행하기.")
+    public void 여러_더하기_수행_Executor() throws InterruptedException {
+        LocalTime lt1 = LocalTime.now();
+        int initalCount = counter.show();
+
+        ExecutorService service = Executors.newFixedThreadPool(maxThreadNumber);
+        CountDownLatch latch = new CountDownLatch(totalCount);
+        for (int i = 0; i < totalCount; i++) {
+            service.submit(() -> {
+                counter.add(counteNumber);
+                latch.countDown();
+            });
+        }
+        latch.await();
+        int finalCount = counter.show();
+        LocalTime lt2 = LocalTime.now();
+        long dif = Duration.between(lt1, lt2).getNano();
+        logger.info("여러_더하기_수행_Executor 테스트가 걸린 시간 : " + ((float)dif / 1000000) + "ms");
+        Assertions.assertEquals(initalCount + totalCount * counteNumber, finalCount);
+    }
+}
diff --git a/src/test/java/com/thread/concurrency/SynchronizedCounterTest.java b/src/test/java/com/thread/concurrency/SynchronizedCounterTest.java
new file mode 100644
index 0000000..7b073b5
--- /dev/null
+++ b/src/test/java/com/thread/concurrency/SynchronizedCounterTest.java
@@ -0,0 +1,51 @@
+package com.thread.concurrency;
+
+import com.thread.concurrency.counter.SynchronizedCounter;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import java.time.Duration;
+import java.time.LocalTime;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+@SpringBootTest
+public class SynchronizedCounterTest {
+
+    private final int counteNumber = 1;
+    private final int totalCount = 5000000;
+    private final int maxThreadNumber = 15;
+    private static final Logger logger = LoggerFactory.getLogger(SynchronizedCounterTest.class);
+
+    @Autowired
+    SynchronizedCounter counter;
+
+    @Test
+    @DisplayName("synchronized로 스레드 안전한 카운터로 동시에 여러 더하기 수행하기.")
+    public void 여러_더하기_수행_Executor() throws InterruptedException {
+
+        LocalTime lt1 = LocalTime.now();
+        int initalCount = counter.show();
+
+        ExecutorService service = Executors.newFixedThreadPool(maxThreadNumber);
+        CountDownLatch latch = new CountDownLatch(totalCount);
+        for (int i = 0; i < totalCount; i++) {
+            service.submit(() -> {
+                counter.add(counteNumber);
+                latch.countDown();
+            });
+        }
+        latch.await();
+        int finalCount = counter.show();
+        LocalTime lt2 = LocalTime.now();
+        long dif = Duration.between(lt1, lt2).getNano();
+        logger.info("여러_더하기_수행_Executor 테스트가 걸린 시간 : " + ((float)dif / 1000000) + "ms");
+        Assertions.assertEquals(initalCount + totalCount * counteNumber, finalCount);
+    }
+}