Abstract
　The San-Riku district has suffered heavily from tsunami waves by reason of rias.
　In this paper the lost poverties caused by the 1896 class tsunami which hit the present Miyako-city were estimated.
　Method was based on the one presented by the Ministry of Construction in "the Statistics of the lost poverties caused by the river floods."
　As the results, the following conclusions were obtained.
1)　The coastal levees of the both sides of the Hei river are too low, as matters now stand, to be effective for the tsunami.
　They may be effective if being get higher about 1.5 metres.
2)　In the plan of the disaster prevention of Miyako-city, the Atago and the Kuwagasaki elementary school are appointed as place of refuge. However we are afraid that they may be flooded, if not being get higher.

*東北大学工学部
Faculty of Engineering, Tohoku University