一般有两种写法，一种是【训令式】，一种是【ヘボン式】。到雅虎jp查一下看看。

【训令式】の表

あいうえお（拗音）あaiueoかkakikukekokyakyukyoさsasisusesosyasyusyoたtatitutetotyatyutyoなnaninunenonyanyunyoはhahihuhehohyahyuhyoまmamimumemomyamyumyoやya(i)yu(e)yoらrarirureroryaryuryoわwa(i)(u)(e)(o)がgagigugegogyagyugyoざzazizuzezozyazyuzyoだda(zi)(zu)dedo(zya)(zyu)(zyo)ばbabibubebobyabyubyoぱpapipupepopyapyupyo

第2表

しゃshaしshiしゅshuしょshoつtsuちゃchaちchiちゅchuちょchoふfuじゃjaじjiじゅjuじょjoぢdiづduぢゃdyaぢゅdyuぢょdyoくゎkwaぐゎgwaをwo

ヘボン式の表

あいうえお（拗音）あaiueoかkakikukekokyakyukyoさsashisusesoshashushoたtachitsutetochachuchoなnaninunenonyanyunyoはhahifuhehohyahyuhyoまmamimumemomyamyumyoやya(i)yu(e)yoらrarirureroryaryuryoわwa(i)(e)(w)oんn(m)がgagigugegogyagyugyoざzajizuzezojajujoだda(ji)(zu)dedo(ja)(ju)(jo)ばbabibubebobyabyubyoぱpapipupepopyapyupyo