han = "= 0123456789()@abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ;:,.+-_/*&";
zen = "＝　０１２３４５６７８９（）＠ａｂｃｄｅｆｇｈｉｊｋｌｍｎｏｐｑｒｓｔｕｖｗｘｙｚＡＢＣＤＥＦＧＨＩＪＫＬＭＮＯＰＱＲＳＴＵＶＷＸＹＺ；：，．＋－＿／＊＆";
function toHankaku(obj){
    var motoText = obj.value;
    str = "";
    for(i=0;i<motoText.length; i++){
        c = motoText.charAt(i);
        n = zen.indexOf(c,0);
        if(n >= 0) c = han.charAt(n);
        str += c;
    }
    obj.value = str;
}