function  randMainImage(){

rndURL = new Array();
rndImg = new Array();
rndAlt = new Array();

rndImg[0] = "http://kaatsu-raccoon.com/wp-content/themes/raccoon/images/image_06.jpg";
rndImg[1] = "http://kaatsu-raccoon.com/wp-content/themes/raccoon/images/image_02.jpg";
rndImg[2] = "http://kaatsu-raccoon.com/wp-content/themes/raccoon/images/image_03.jpg";
rndImg[3] = "http://kaatsu-raccoon.com/wp-content/themes/raccoon/images/image_04.jpg";
rndImg[4] = "http://kaatsu-raccoon.com/wp-content/themes/raccoon/images/image_05.jpg";

rndURL[0] = "http://kaatsu-raccoon.com/kouka/";
rndURL[1] = "http://kaatsu-raccoon.com/kouka/";
rndURL[2] = "http://kaatsu-raccoon.com/kouka/";
rndURL[3] = "http://kaatsu-raccoon.com/kouka/";
rndURL[4] = "http://kaatsu-raccoon.com/kouka/";

rndAlt[0] = "ラクーン0";
rndAlt[1] = "ラクーン1";
rndAlt[2] = "ラクーン2";
rndAlt[3] = "ラクーン3";
rndAlt[4] = "ラクーン4";

rnd = Math.floor(Math.random() * (rndURL.length));

mainImgGenerate = document.getElementById('main_image');

var viewTemp ='<a href="' + rndURL[rnd] + '"><img src="' + rndImg[rnd]  +'" alt="' + rndAlt[rnd] + '" /></a>';

mainImgGenerate.innerHTML = viewTemp;

}

function  changeMainImage(){

mainImgGenerate = document.getElementById('main_image');

var viewTemp ='<a href="' + rndURL[imageId] + '"><img src="' + rndImg[imageId]  +'" alt="' + rndAlt[imageId] + '" /></a>';

mainImgGenerate.innerHTML = viewTemp;

}