diff --git a/src/common/constants.ts b/src/common/constants.ts
new file mode 100644
index 0000000..80b9674
--- /dev/null
+++ b/src/common/constants.ts
@@ -0,0 +1,21 @@
+export const DEFAULT_INSTANCE_URL = "https://misskey.io";
+
+/**
+ * リプライボタンの文字列一覧
+ */
+export const REPLY_BUTTON_LABELS = [
+  "返信",
+  "Reply",
+  "답글",
+  "回复",
+  "回覆",
+  "Répondre",
+  "Responder",
+  "Antworten",
+  "Rispondi",
+  "Responder",
+  "Responder",
+  "Antwoorden",
+  "Svara",
+  "Svar",
+];
diff --git a/src/content_script/TwitterCrawler.ts b/src/content_script/TwitterCrawler.ts
index 0cf053d..db97622 100644
--- a/src/content_script/TwitterCrawler.ts
+++ b/src/content_script/TwitterCrawler.ts
@@ -1,3 +1,4 @@
+import { DEFAULT_INSTANCE_URL } from '../common/constants';
 import { postToMisskey, Image } from './MisskeyAPI'
 import { showNotification } from './Notification'
 import { Scope } from './ScopeModal'; 
@@ -44,7 +45,7 @@ const getToken = async () => {
 const getServer = async () => {
   return await new Promise<string>((resolve, reject) => {
     chrome.storage.sync.get(['misskey_server'], (result) => {
-      let server = result.misskey_server ?? "https://misskey.io";
+      let server = result.misskey_server ?? DEFAULT_INSTANCE_URL;
       if (server.endsWith('/')) {
         server = server.slice(0, -1)
       }
diff --git a/src/content_script/content_script.tsx b/src/content_script/content_script.tsx
index e9515a3..510c20d 100644
--- a/src/content_script/content_script.tsx
+++ b/src/content_script/content_script.tsx
@@ -1,6 +1,7 @@
 import { tweetToMisskey } from './TwitterCrawler';
 import { flag_icon } from './Icons'
 import { isShowingScopeModal, showScopeModal, closeScopeModal, updateScopeButton } from './ScopeModal';
+import { REPLY_BUTTON_LABELS } from '../common/constants';
 
 const gifButtonSelector = 'div[data-testid="gifSearchButton"]'
 const buttonSelector = 'div[data-testid="tweetButton"], div[data-testid="tweetButtonInline"]'
@@ -179,10 +180,6 @@ const addMisskeyImageOptionButton = (editButton: HTMLElement, attachmentsImage:
 
 }
 
-
-// リプライボタンの文字列一覧
-const replyButtonLabels = [ "返信", "Reply", "답글", "回复", "回覆", "Répondre", "Responder", "Antworten", "Rispondi", "Responder", "Responder", "Antwoorden", "Svara", "Svar" ];
-
 const foundTweetButtonHandler = (tweetButton: HTMLElement) => {
   if (!tweetButton) return;
 
@@ -215,8 +212,14 @@ const observer = new MutationObserver(mutations => {
         if (node.nodeType !== Node.ELEMENT_NODE) return;
         
         const tweetButton = node.querySelector(buttonSelector);
-        if (tweetButton) { foundTweetButtonHandler(tweetButton); }
-
+        if (tweetButton) { 
+          // リプライボタンの場合は後続の処理を行わない
+          const isReplyButton = REPLY_BUTTON_LABELS.indexOf(tweetBox.innerText) !== -1;
+          if (isReplyButton) return;
+          foundTweetButtonHandler(tweetButton); 
+          return;
+        }
+        
         const attachmentsImages = document.querySelectorAll(attachmentsImageSelector);
         if (attachmentsImages) { 
           attachmentsImages.forEach((attachmentsImage: any) => {
diff --git a/src/popup/Popup.tsx b/src/popup/Popup.tsx
index 6cff077..0b5b221 100644
--- a/src/popup/Popup.tsx
+++ b/src/popup/Popup.tsx
@@ -1,10 +1,11 @@
 import React, { useEffect, useState } from "react"
 import ReactDOM from "react-dom"
-import { Container, Typography, AppBar, Toolbar, TextField, Link, FormControlLabel, Checkbox } from "@mui/material"
+import { Container, Typography, AppBar, Toolbar, TextField, FormControlLabel, Checkbox } from "@mui/material"
+import { DEFAULT_INSTANCE_URL } from "../common/constants";
 
 const Popup = () => {
   const [token, setToken] = useState<string | null>(null)
-  const [server, setServer] = useState<string | null>("https://misskey.io")
+  const [server, setServer] = useState<string | null>(DEFAULT_INSTANCE_URL);
   const [cw, setCw] = useState<boolean | null>(null)
   const [sensitive, setSensitive] = useState<boolean | null>(null)
   const [showAccess, setShowAccess] = useState<boolean|null>(null)
@@ -65,7 +66,7 @@ const Popup = () => {
 
         <TextField  
           label="Server URL"
-          placeholder="https://misskey.io"
+          placeholder={DEFAULT_INSTANCE_URL}
           value={server}
           variant="outlined"
           fullWidth