diff --git a/src/components/auth/Join.jsx b/src/components/auth/Join.jsx
index f414cd62..4062d313 100644
--- a/src/components/auth/Join.jsx
+++ b/src/components/auth/Join.jsx
@@ -98,6 +98,10 @@ export default function Join() {
       alert(getMessage('common.message.required.data', [getMessage('join.sub1.fax')]))
       faxRef.current.focus()
       return false
+    }else if (!telRegex.test(fax)) {
+      alert(getMessage('join.validation.check1', [getMessage('join.sub1.fax')]))
+      faxRef.current.focus()
+      return false
     }
 
     const bizNo = formData.get('bizNo')
@@ -174,6 +178,10 @@ export default function Join() {
       alert(getMessage('common.message.required.data', [getMessage('join.sub2.fax')]))
       userFaxRef.current.focus()
       return false
+    } else if (!telRegex.test(userFax)) {
+      alert(getMessage('join.validation.check1', [getMessage('join.sub2.fax')]))
+      userFaxRef.current.focus()
+      return false
     }
 
     return true
@@ -349,7 +357,15 @@ export default function Join() {
                       <th>{getMessage('join.sub1.fax')}<span className="important">*</span></th>
                       <td>
                         <div className="input-wrap" style={{ width: '200px' }}>
-                          <input type="text" id="fax" name="fax" className="input-light" maxLength={15} onChange={inputNumberCheck} ref={faxRef} />
+                          <input
+                            type="text"
+                            id="fax"
+                            name="fax"
+                            className="input-light"
+                            maxLength={15}
+                            placeholder={getMessage('join.sub1.telNo_placeholder')}
+                            onChange={inputTelNumberCheck}
+                            ref={faxRef} />
                         </div>
                       </td>
                     </tr>
@@ -466,7 +482,8 @@ export default function Join() {
                             name="userFax"
                             className="input-light"
                             maxLength={15}
-                            onChange={inputNumberCheck}
+                            placeholder={getMessage('join.sub1.telNo_placeholder')}
+                            onChange={inputTelNumberCheck}
                             ref={userFaxRef}
                           />
                         </div>