var txt = new Array();
txt[0]="<a href='http://www.123-navi.com/epcschool/'><img src='http://www.123-navi.com/bana/009_epc.jpg'  width='100%' border=0></a>";
txt[1]="<a href='http://www.123-navi.com/cost-souken/'><img src='http://www.123-navi.com/bana/010_cost.jpg'  width='100%' border=0></a>";
txt[2]="<a href='http://www.123-navi.com/mensuke/'><img src='http://www.123-navi.com/bana/027_mensuke.gif'  width='100%' border=0></a>";
txt[3]="<a href='http://www.123-navi.com/onestarbar/'><img src='http://www.123-navi.com/bana/020_onestaber.jpg'  width='100%' border=0></a>";
txt[4]="<a href='http://www.123-navi.com/interior-sawajiri/'><img src='http://www.123-navi.com/bana/006_sawajiri.gif'  width='100%' border=0></a>";

mmax = 5; //メッセージ行数
txtno = Math.floor(Math.random() * mmax);
document.write(txt[txtno]);