myModify = document.lastModified;
myD = new Date(myModify);
myYear = myD.getYear();
myYear4 = (myYear < 2000) ? myYear+1900 : myYear;
myMonth = myD.getMonth() + 1; 
myDate = myD.getDate(); 
myStr = "最新更新日 " + myYear4 + "." + myMonth + "." + myDate;
document.write( myStr );