Ishibutai Kofun (石舞台古墳) is a stone kofun tumulus of the Asuka period in the east of Shimanoshō, Asuka, Nara Prefecture, Japan. The kofun is believed to be the tomb of Soga no Umako. It occupies a space of 54 m (177 ft), and is the largest known megalithic structure in Japan.