var GISURL = "http://lsweb1.ess.bosai.go.jp/lsweb_jp_new/gis/map_blue.html?";
var geocoder = new GClientGeocoder();

function getCoordinates(address){
   var address = document.myForm.address.value;
   if (address != ''){
     geocoder.getLatLng(address,function(point){
      if (point != null){
         document.myForm.lat.value = point.lat();
         document.myForm.lng.value = point.lng();
         location.href =  GISURL + "x=" + document.myForm.lng.value + "&y=" + document.myForm.lat.value + "&s=50000" + "&a=" +  encodeURI(document.myForm.address.value);
       } else{
           alert("入力した住所は見つかりませんでした");
       }
     })
	}
   else{
      alert("住所や地名を入力してください");
  }
}