diff --git a/builder/article.go b/builder/article.go
index c5e37868..dbfeb0fa 100644
--- a/builder/article.go
+++ b/builder/article.go
@@ -30,6 +30,7 @@ type Article struct {
 	HowTo       *HowTo           `yaml:"howto"`
 	BreadCrumb  []BreadCrumbItem `yaml:"breadcrumb"`
 	Layout      string           `yaml:"layout"`
+	Hidden	    bool             `yaml:"hidden"`
 
 	Markdown []byte        `yaml:"-"`
 	Content  template.HTML `yaml:"-"`
diff --git a/builder/autoindex.go b/builder/autoindex.go
index 50091ad6..740b36a2 100644
--- a/builder/autoindex.go
+++ b/builder/autoindex.go
@@ -513,13 +513,20 @@ type SitemapContext struct {
 }
 
 func (g *IndexGenerator) generateSitemap(dst fs.Writable, articles ArticleList, conf Config) (ArtifactList, error) {
+	as := make(ArticleList, 0, len(articles))
+	for _, a := range articles {
+		if !a.Hidden {
+			as = append(as, a)
+		}
+	}
+
 	targetPath := "sitemap.xml"
 	result := ArtifactList{Index{
 		name:    targetPath,
-		sources: articles.Sources(),
+		sources: as.Sources(),
 	}}
 
-	if fs.ModTime(dst, targetPath).After(articles.ModTime()) {
+	if fs.ModTime(dst, targetPath).After(as.ModTime()) {
 		return result, nil
 	}
 
@@ -535,7 +542,7 @@ func (g *IndexGenerator) generateSitemap(dst fs.Writable, articles ArticleList,
 
 	err = tmpl.Execute(output, SitemapContext{
 		URL:   "https://blanktar.jp/sitemap.xml",
-		Pages: articles,
+		Pages: as,
 	})
 	if err != nil {
 		output.Close()
diff --git a/pages/404.md b/pages/404.md
new file mode 100644
index 00000000..f3abe594
--- /dev/null
+++ b/pages/404.md
@@ -0,0 +1,6 @@
+---
+layout: error.html
+title: 404
+description: ページが見つかりません
+hidden: true
+---
diff --git a/templates/error.html b/templates/error.html
new file mode 100644
index 00000000..1d345b2f
--- /dev/null
+++ b/templates/error.html
@@ -0,0 +1,41 @@
+{{define "title"}}{{.Description}} - Blanktar{{end}}
+
+{{/* <style> */}}    
+{{define "style"}}
+html, body {
+    height: 100%;
+}
+main {
+    display: flex;
+    flex-direction: column;
+    justify-content: center;
+    align-items: center;
+    height: 100%;
+    overflow: hidden;
+}
+div > span {
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    position: fixed;
+    top: 0;
+    left: 0;
+    width: 100%;
+    height: 100%;
+    font-size: 4000%;
+    opacity: 0.05;
+    user-select: none;
+    z-index: -1;
+}
+{{end}}
+{{/* </style> */}}
+
+{{define "body"}}
+    <main>
+        <div>
+            <span>{{.Title}}</span>
+            <h1>{{.Description}}</h1>
+            <p>→ <a href="/">トップページに戻る</a></p>
+        </div>
+    </main>
+{{end}}