preload_img = new image();
 preload_img.src = 'image/button1b.jpg';
 preload_img = new image();
 preload_img.src = 'image/button2b.jpg';
 preload_img = new image();
 preload_img.src = 'image/button3b.jpg';
 preload_img = new image();
 preload_img.src = 'image/button4b.jpg';
 preload_img = new image();
 preload_img.src = 'image/button5b.jpg';
 preload_img = new image();
 preload_img.src = 'image/button6b.jpg';
 preload_img = new image();
 preload_img.src = 'image/button7b.jpg';
 preload_img = new image();
 preload_img.src = 'image/button8b.jpg';
 preload_img = new image();
 preload_img.src = 'image/button9sitemap2.jpg';
 preload_img = new image();
 preload_img.src = 'image/button10toiawase2.jpg';
 preload_img = new image();
 preload_img.src = 'image/button11twitter2.jpg';
 preload_img = new image();
 preload_img.src = 'image/button12link2.jpg';
 preload_img = new image();
 preload_img.src = 'image/button13.jpg';
 preload_img = new image();
 preload_img.src = 'image/button14.jpg';
 preload_img = new image();
 preload_img.src = 'image/button15.jpg';