diff --git a/EffectiveCSharp/EffectiveCSharp.sln b/EffectiveCSharp/EffectiveCSharp.sln
new file mode 100644
index 0000000..a01922f
--- /dev/null
+++ b/EffectiveCSharp/EffectiveCSharp.sln
@@ -0,0 +1,25 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.8.34511.84
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EffectiveCSharp", "EffectiveCSharp\EffectiveCSharp.csproj", "{1B79263C-F9E0-4FAC-8550-E91173EB3A2F}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{1B79263C-F9E0-4FAC-8550-E91173EB3A2F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{1B79263C-F9E0-4FAC-8550-E91173EB3A2F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{1B79263C-F9E0-4FAC-8550-E91173EB3A2F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{1B79263C-F9E0-4FAC-8550-E91173EB3A2F}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {18E619C9-0514-4336-A32F-36E7B1205A92}
+	EndGlobalSection
+EndGlobal
diff --git a/EffectiveCSharp/EffectiveCSharp/EffectiveCSharp.csproj b/EffectiveCSharp/EffectiveCSharp/EffectiveCSharp.csproj
new file mode 100644
index 0000000..74abf5c
--- /dev/null
+++ b/EffectiveCSharp/EffectiveCSharp/EffectiveCSharp.csproj
@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>
diff --git a/EffectiveCSharp/EffectiveCSharp/LanguageComponent/CallEvent.cs b/EffectiveCSharp/EffectiveCSharp/LanguageComponent/CallEvent.cs
new file mode 100644
index 0000000..6c8afc2
--- /dev/null
+++ b/EffectiveCSharp/EffectiveCSharp/LanguageComponent/CallEvent.cs
@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace EffectiveCSharp.LanguageComponent
+{
+    internal class CallEvent
+    {
+        public event EventHandler<string> Event;
+
+        public void Work()
+        {
+            int cnt = 0;
+            while (cnt < 10)
+            {
+                cnt++;
+                RaiseUpdate(cnt.ToString());
+
+                Thread.Sleep(1000);
+            }
+        }
+
+        private void RaiseUpdate(string contents)
+        {
+            Event?.Invoke(this, contents);
+        }
+    }
+}
diff --git a/EffectiveCSharp/EffectiveCSharp/Program.cs b/EffectiveCSharp/EffectiveCSharp/Program.cs
new file mode 100644
index 0000000..31ed4be
--- /dev/null
+++ b/EffectiveCSharp/EffectiveCSharp/Program.cs
@@ -0,0 +1,15 @@
+using EffectiveCSharp.LanguageComponent;
+
+namespace EffectiveCSharp
+{
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            CallEvent callEvent = new CallEvent();
+            callEvent.Event += (s, e) => Console.WriteLine(e);
+            callEvent.Work();
+        }
+
+    }
+}