diff --git a/Chat/Client/Singleton.cs b/Chat/Client/Singleton.cs
index 0dbb40f..c10d926 100644
--- a/Chat/Client/Singleton.cs
+++ b/Chat/Client/Singleton.cs
@@ -13,6 +13,8 @@ namespace Client
 	{
 		public static Singleton Instance { get; set; } = new Singleton();
 
+		public readonly int HEARTBEAT_INTERVAL = 5000;
+
 		public string Id { get; set; } = "";
 		public string Nickname { get; set; } = "";
 		public Socket Socket { get; } = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
@@ -45,6 +47,13 @@ namespace Client
 			Socket socket = (Socket)sender;
 			byte[] headerBuffer = new byte[2];
 
+			System.Timers.Timer timer = new System.Timers.Timer(HEARTBEAT_INTERVAL);
+			timer.Elapsed += async (sender, e) =>
+			{
+				HeartbeatPacket packet = new HeartbeatPacket();
+				await socket.SendAsync(packet.Serialize(), SocketFlags.None);
+			};
+
 			try
 			{
 				while (true)
@@ -54,6 +63,8 @@ namespace Client
 					if (n1 < 1)
 					{
 						Console.WriteLine($"[{DateTime.Now}] Disconnect server: {socket.RemoteEndPoint}");
+						
+						timer.Stop();
 						socket.Dispose();
 						return;
 					}
@@ -78,6 +89,8 @@ namespace Client
 					{
 						LoginResponsePacket packet = new LoginResponsePacket(dataBuffer);
 						LoginResponsed?.Invoke(packet, EventArgs.Empty);
+
+						timer.Start();
 					}
 					else if (packetType == PacketType.CreateRoomResponse)
 					{
diff --git a/Chat/Core/HeartbeatPacket.cs b/Chat/Core/HeartbeatPacket.cs
new file mode 100644
index 0000000..d53baed
--- /dev/null
+++ b/Chat/Core/HeartbeatPacket.cs
@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Core
+{
+	public class HeartbeatPacket : IPacket
+	{
+		public byte[] Serialize()
+		{
+			byte[] packetType = BitConverter.GetBytes(IPAddress.HostToNetworkOrder((short)PacketType.Heartbeat));
+
+			short dataSize = (short)(packetType.Length);
+			byte[] header = BitConverter.GetBytes(IPAddress.HostToNetworkOrder(dataSize));
+
+			byte[] buffer = new byte[2 + dataSize];
+
+			int cursor = 0;
+			Array.Copy(header, 0, buffer, cursor, header.Length);
+			cursor += header.Length;
+
+			Array.Copy(packetType, 0, buffer, cursor, packetType.Length);
+
+			return buffer;
+		}
+	}
+}
diff --git a/Chat/Core/PServer.cs b/Chat/Core/PServer.cs
index 43e3c5a..c23ea3a 100644
--- a/Chat/Core/PServer.cs
+++ b/Chat/Core/PServer.cs
@@ -11,6 +11,9 @@ namespace Core
 {
 	public class PServer
 	{
+		private readonly int HEARTBEAT_INTERVAL = 5000;
+		private readonly int HEARTBEAT_THREASHOLD = 5;
+
 		private Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
 		
 		public ConcurrentDictionary<string, Room> Rooms { get; } = new ConcurrentDictionary<string, Room>();
@@ -56,8 +59,19 @@ namespace Core
 			{
 				while (true)
 				{
+					Task task1 = Task.Delay(HEARTBEAT_INTERVAL * HEARTBEAT_THREASHOLD);
 					// header buffer
-					int n1 = await clientSocket.ReceiveAsync(headerBuffer, SocketFlags.None);
+					Task<int> task2 = clientSocket.ReceiveAsync(headerBuffer, SocketFlags.None);
+
+					Task result = await Task.WhenAny(task1, task2);
+					if (result == task1)
+					{
+						Console.WriteLine($"[{DateTime.Now}] Disconnect client - {clientSocket.RemoteEndPoint}");
+						await Remove(id, nickname, roomName, clientSocket);
+						return;
+					}
+
+					int n1 = await task2;
 					if (n1 < 1)
 					{
 						Console.WriteLine($"[{DateTime.Now}] Disconnect client - {clientSocket.RemoteEndPoint}");
@@ -195,6 +209,10 @@ namespace Core
 							}
 						}
 					}
+					else if (packetType == PacketType.Heartbeat)
+					{
+						Console.WriteLine($"[{DateTime.Now}] Heartbeat from client - {clientSocket.RemoteEndPoint} (id: {id}, nickname: {nickname})");
+					}
 				}
 			}
 			catch (Exception ex)
diff --git a/Chat/Core/PacketType.cs b/Chat/Core/PacketType.cs
index a686746..1218db1 100644
--- a/Chat/Core/PacketType.cs
+++ b/Chat/Core/PacketType.cs
@@ -19,6 +19,7 @@ namespace Core
 		UserEnter,
 		UserLeave,
 		Chat,
-		Duplicate
+		Duplicate,
+		Heartbeat,
 	}
 }