var tourokusu;

tourokusu = 1;
var msg = new Array(tourokusu);
msg[0] = "<A HREF=\"http://www.amazon.co.jp/exec/obidos/redirect?tag=freem-22&path=tg/browse/-/489986\" target=blank><IMG SRC=\"http://www.freem.ne.jp/contents/pic/ad/multiproduct_v3_468_anime.gif\" alt=\" Amazon.co.jpアソシエイト\" BORDER=\"0\" HEIGHT=\"60\" WIDTH=\"468\"></A>";

taisyou = Math.floor(Math.random()*tourokusu);
document.write( msg[taisyou] );