JavaScript で数値を3桁区切り function toReadableNumber(str){ var ret = Math.floor(str).toString(); ret = ret.match(/./g).reverse().join(""); ret = ret.replace(/(\d{3})/g,"$1,"); ret = ret.match(/./g).reverse().join("").replace(/^,/,""); return ret; } - Reference きんがくとかをけたくぎり http://page.freett.com/elledia/tips/comma.html