diff --git a/.github/workflows/CheckLicense.yml b/.github/workflows/CheckLicense.yml
new file mode 100644
index 000000000..4a06708c0
--- /dev/null
+++ b/.github/workflows/CheckLicense.yml
@@ -0,0 +1,21 @@
+name: "Validate License Header"
+
+on:
+  push:
+    branches: [ main, develop, 'feature/**' ]
+  pull_request:
+    branches: [ main, develop, 'feature/**' ]
+
+jobs:
+  test:
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v1.8.1
+        with:
+          dotnet-version: 5.0.301
+      - name: Setup C# Interactive
+        run: dotnet tool install -g dotnet-script
+      - name: Validate
+        run: dotnet script Tools/LicenseHeader/Validate.csx .
diff --git a/Tools/LicenseHeader/Validate.csx b/Tools/LicenseHeader/Validate.csx
new file mode 100644
index 000000000..81b152402
--- /dev/null
+++ b/Tools/LicenseHeader/Validate.csx
@@ -0,0 +1,89 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#nullable enable
+
+if (Args.Count != 1) {
+	WriteLine("対象のディレクトリを指定してください。");
+	return;
+}
+
+string   dir           = Path.GetFullPath(Args[0]);
+string[] files         = Directory.GetFiles(dir, "*", SearchOption.AllDirectories);
+var      invalid_files = new List<string>();
+
+WriteLine("対象のディレクトリ：" + dir);
+WriteLine();
+
+for (int i = 0; i < files.Length; ++i) {
+	string file = files[i];
+	string ext  = Path.GetExtension(file);
+	WriteLine("\"{0}\" を確認しています . . .", file);
+	if (!Ignore(file) && ext is ".cs" or ".csx" or ".strings" or ".xml" or ".xaml" or ".resx"
+		or ".axml" or ".storyboard" or ".bat" or ".cmd" or ".sh" or ".tf" or ".yml" or ".feature") {
+		using (var fs = new FileStream(file, FileMode.Open, FileAccess.ReadWrite, FileShare.None))
+		using (var sr = new StreamReader(fs, true)) {
+			if (Validate(sr.ReadToEnd())) {
+				WriteLine("ライセンス通知は記述されています。");
+			} else {
+				invalid_files.Add(file);
+				ForegroundColor = ConsoleColor.Red;
+				WriteLine("ライセンス通知は記述されていません。");
+				ResetColor();
+			}
+		}
+	} else {
+		WriteLine("このファイルは無視されます。");
+	}
+	WriteLine();
+}
+
+WriteLine();
+
+int count = invalid_files.Count;
+if (count == 0) {
+	WriteLine("ライセンス通知は全てのファイルに記述されています。");
+} else {
+	var sb = new StringBuilder();
+	sb.AppendLine("ライセンス通知が記述されていないファイルがあります。");
+	for (int i = 0; i < count; ++i) {
+		sb.Append(" - ").AppendLine(invalid_files[i]);
+	}
+	ForegroundColor = ConsoleColor.Red;
+	WriteLine(sb.ToString());
+	Environment.Exit(-1);
+}
+
+
+/*================================================================================================*/
+
+const string HEADER_LINE_1  = "This Source Code Form is subject to the terms of the Mozilla Public";
+const string HEADER_LINE_2  = "License, v. 2.0. If a copy of the MPL was not distributed with this";
+const string HEADER_LINE_3  = "file, You can obtain one at http://mozilla.org/MPL/2.0/.";
+const string HEADER_LINE_3s = "file, You can obtain one at https://mozilla.org/MPL/2.0/.";
+
+/// <summary>検証</summary>
+public static bool Validate(string data)
+{
+	if ((data.Contains(HEADER_LINE_1) && data.Contains(HEADER_LINE_2)) &&
+		(data.Contains(HEADER_LINE_3) || data.Contains(HEADER_LINE_3s))) {
+		return true;
+	} else {
+		return false;
+	}
+}
+
+/// <summary>除外設定</summary>
+public static bool Ignore(string file)
+{
+	return file.EndsWith(".designer.cs")
+		|| file.EndsWith(".Designer.cs")
+		|| file.EndsWith(".feature.cs")
+		|| file.Contains("Xamarin.ExposureNotification")
+		|| file.Contains("bin")
+		|| file.Contains("Bin")
+		|| file.Contains("obj")
+		|| file.Contains("Obj")
+		|| file.Contains(".github");
+}