if ((navigator.userAgent.indexOf('iPhone') != -1) || 
    (navigator.userAgent.indexOf('iPod') != -1)) {
　　if(confirm('iPhone向けのページを表示しますか？')){
var host = location.hostname;
var path = location.pathname;
var path = path.replace("/mt/","/mt/i/");
var url = "http://" + host + path;
    location.href = url; }
}