This paper describe the characteristics of the floodways in Japan through the history of their development. The object channels are 327 that the all floodways to be called in Japan today. A research adopts the method that inspects the attribute of the floodway individually in the outlet form, the diversion structure and the development year etc. As the second step, the correlation of each attribute had been considered. As a result, it was found that the Otozu River is oldest in the history of the floodway development, in the channels that discharges only flood that exist.