簡単な例だけ。
HTML
1<html>
2 <head>
3 <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.0/jquery.min.js"></script>
4 <script>
5 $(function($) {
6 $('#numSelect').change(function() {
7 $('#inputForms').empty();
8 for(var i = 0; i < $(this).val(); i++){
9 var addForm = $('<input type="text" placeholder="氏名入力">');
10 $('#inputForms').append(addForm);
11 }
12 });
13 });
14 </script>
15 </head>
16 <body>
17 <select id="numSelect" name="numSelect">
18 <option value="1" selected>1人</option>
19 <option value="2">2人</option>
20 <option value="3">3人</option>
21 <option value="4">4人</option>
22 <option value="5">5人</option>
23 </select>
24 <div id="inputForms">
25 <input type="text" placeholder="氏名入力"></input>
26 <div>
27 </body>
28</html>