diff --git a/backend/app/controllers/wiki_pages_controller.rb b/backend/app/controllers/wiki_pages_controller.rb
index a778b48..abe29f0 100644
--- a/backend/app/controllers/wiki_pages_controller.rb
+++ b/backend/app/controllers/wiki_pages_controller.rb
@@ -13,6 +13,22 @@ class WikiPagesController < ApplicationController
     render_wiki_page_or_404 WikiPage.find_by(title: params[:title])
   end
 
+  def exists
+    if WikiPage.exists?(params[:id])
+      head :no_content
+    else
+      head :not_found
+    end
+  end
+
+  def exists_by_title
+    if WikiPage.exists?(title: params[:title])
+      head :no_content
+    else
+      head :not_found
+    end
+  end
+
   def diff
     id = params[:id]
     from = params[:from]
diff --git a/backend/config/routes.rb b/backend/config/routes.rb
index 0733991..206d1a6 100644
--- a/backend/config/routes.rb
+++ b/backend/config/routes.rb
@@ -1,46 +1,60 @@
 Rails.application.routes.draw do
-  get 'tags/nico', to: 'nico_tags#index'
-  put 'tags/nico/:id', to: 'nico_tags#update'
-  get 'tags/autocomplete', to: 'tags#autocomplete'
-  get 'tags/name/:name', to: 'tags#show_by_name'
-  get 'posts/random', to: 'posts#random'
-  get 'posts/changes', to: 'posts#changes'
-  post 'posts/:id/viewed', to: 'posts#viewed'
-  delete 'posts/:id/viewed', to: 'posts#unviewed'
-  get 'preview/title', to: 'preview#title'
-  get 'preview/thumbnail', to: 'preview#thumbnail'
-  get 'wiki/title/:title', to: 'wiki_pages#show_by_title'
-  get 'wiki/search', to: 'wiki_pages#search'
-  get 'wiki/changes', to: 'wiki_pages#changes'
-  get 'wiki/:id/diff', to: 'wiki_pages#diff'
-  get 'wiki/:id', to: 'wiki_pages#show'
-  get 'wiki', to: 'wiki_pages#index'
-  post 'wiki', to: 'wiki_pages#create'
-  put 'wiki/:id', to: 'wiki_pages#update'
-  post 'users/code/renew', to: 'users#renew'
-
-  resources :posts
-  resources :ip_addresses
-  resources :nico_tag_relations
-  resources :post_tags
-  resources :settings
-  resources :tag_aliases
-  resources :tags
-  resources :user_ips
-  resources :user_post_views
+  resources :nico_tags, path: 'tags/nico', only: [:index, :update]
+
+  resources :tags do
+    collection do
+      get :autocomplete
+      get 'name/:name', action: :show_by_name
+    end
+  end
+
+  scope :preview, controller: :preview do
+    get :title
+    get :thumbnail
+  end
+
+  resources :wiki_pages, path: 'wiki', only: [:index, :show, :create, :update] do
+    collection do
+      get :search
+      get :changes
+
+      scope :title do
+        get ':title/exists', action: :exists_by_title
+        get ':title', action: :show_by_title
+      end
+    end
+
+    member do
+      get :exists
+      get :diff
+    end
+  end
+
+  resources :posts do
+    collection do
+      get :random
+      get :changes
+    end
+
+    member do
+      post :viewed
+      delete :viewed, action: :unviewed
+    end
+  end
+
   resources :users, only: [:create, :update] do
     collection do
       post :verify
       get :me
+      post 'code/renew', action: :renew
     end
   end
 
-  # Define your application routes per the DSL in https://guides.rubyonrails.org/routing.html
-
-  # Reveal health status on /up that returns 200 if the app boots with no exceptions, otherwise 500.
-  # Can be used by load balancers and uptime monitors to verify that the app is live.
-  # get "up" => "rails/health#show", as: :rails_health_check
-
-  # Defines the root path route ("/")
-  # root "posts#index"
+  resources :ip_addresses
+  resources :nico_tag_relations
+  resources :post_tags
+  resources :settings
+  resources :tag_aliases
+  resources :user_ips
+  resources :user_post_views
 end
diff --git a/frontend/src/components/TagLink.tsx b/frontend/src/components/TagLink.tsx
index a77ca5f..ee673cc 100644
--- a/frontend/src/components/TagLink.tsx
+++ b/frontend/src/components/TagLink.tsx
@@ -1,5 +1,8 @@
+import axios from 'axios'
+import { useEffect, useState } from 'react'
 import { Link } from 'react-router-dom'
 
+import { API_BASE_URL } from '@/config'
 import { LIGHT_COLOUR_SHADE, DARK_COLOUR_SHADE, TAG_COLOUR } from '@/consts'
 import { cn } from '@/lib/utils'
 
@@ -27,6 +30,27 @@ export default (({ tag,
 		   withWiki  = true,
 		   withCount = true,
 		   ...props }: Props) => {
+  const [havingWiki, setHavingWiki] = useState (true)
+
+  const wikiExists = async (tagName: string) => {
+    try
+    {
+      await axios.get (`${ API_BASE_URL }/wiki/title/${ encodeURIComponent (tagName) }/exists`)
+      setHavingWiki (true)
+    }
+    catch
+    {
+      setHavingWiki (false)
+    }
+  }
+
+  useEffect (() => {
+    if (!(linkFlg) || !(withWiki))
+      return
+
+    wikiExists (tag.name)
+  }, [tag.name, linkFlg, withWiki])
+
   const spanClass = cn (
       `text-${ TAG_COLOUR[tag.category] }-${ LIGHT_COLOUR_SHADE }`,
       `dark:text-${ TAG_COLOUR[tag.category] }-${ DARK_COLOUR_SHADE }`)
@@ -39,10 +63,19 @@ export default (({ tag,
       <>
 	{(linkFlg && withWiki) && (
 	    <span className="mr-1">
-	      <Link to={`/wiki/${ encodeURIComponent (tag.name) }`}
-		    className={linkClass}>
-		?
-	      </Link>
+	      {havingWiki
+	       ? (
+		  <Link to={`/wiki/${ encodeURIComponent (tag.name) }`}
+			className={linkClass}>
+		    ?
+		  </Link>)
+	       : (
+		  <Link to={`/wiki/${ encodeURIComponent (tag.name) }`}
+			className="animate-[wiki-blink_.25s_steps(2,end)_infinite]
+				   dark:animate-[wiki-blink-dark_.25s_steps(2,end)_infinite]"
+			title={`${ tag.name } Wiki が存在しません．`}>
+		    !
+		  </Link>)}
 	    </span>)}
 	{nestLevel > 0 && (
 	    <span
diff --git a/frontend/src/index.css b/frontend/src/index.css
index 6cfa0bc..263b75d 100644
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@@ -96,3 +96,15 @@ button:focus-visible
     background-color: #f9f9f9;
   }
 }
+
+@keyframes wiki-blink
+{
+  0%, 100% { color: #dc2626; }
+  50% { color: #2563eb; }
+}
+
+@keyframes wiki-blink-dark
+{
+  0%, 100% { color: #f87171; }
+  50% { color: #60a5fa; }
+}