function keika(nen,tsuki,hi,nenhyoki)
{
  var fd=new Date(nen,tsuki-1,hi);
  var td=new Date();
  var ld=new Date(td.getFullYear(),td.getMonth(),0);
  var dify,difm,difd;
  var yflg=0;
  var mflg=0;
  if(td.getDate()>=fd.getDate()){
    difd=td.getDate()-fd.getDate();
  }else{
    if(ld.getDate()>=fd.getDate()){
      difd=(ld.getDate()-fd.getDate())+td.getDate();
    }else{
      difd=td.getDate();
    }
    mflg=1;
  }
  if(td.getMonth()-mflg>=fd.getMonth()){
    difm=td.getMonth()-mflg-fd.getMonth();
  }else{
    difm=12+td.getMonth()-mflg-fd.getMonth();
    yflg=1;
  }
  dify=td.getFullYear()-yflg-fd.getFullYear();
  var hyoji="";
  if(dify>0)hyoji=dify+nenhyoki;
  if(difm>0)hyoji=hyoji+difm+"ヶ月と";
  if(difd>0)hyoji=hyoji+difd+"日";
  return(hyoji);
}
document.write("イイナ:2006/8/20~ "+keika(2006,8,20,"年"));
document.write("<br>ななみ:2006/12/10~ "+keika(2006,12,10,"年"));
document.write("<br>美実香:2007/1/27~ "+keika(2007,1,27,"年"));