Recurrence times of the slope failure during the last 930 years were revealed with tephrochronological method. Two regions in central Hokkaido, where severe rainfall disasters occurred recently, were selected as investigated areas. Two airfall tephra: Us-c erupthd in A. D. 1663 and B-Tm in about 930 years ago were used for key layers. Sediments were classified into three types: talus cone, alluvial cone and alluvial fan. Trenches dug out on the sediments were observed and recurrence times of the slope failure were estimated by counting failure deposits above tephra layers. Average of the slope failure during the last 300 years was 1. 3 times in the marine terrace and 1. 8 times in the pyroclastic flow plateau. With respect to the sediment morphology, several mudflow deposits were observed in the alluvial fan and talus cone, whereas deposits in alluvial cone was very few. As the result, active and dormant types were recognized regarding to the catchment failure activity. The former type implied that the slope failure had recurred during the last 300 years, whereas the latter implied that the slope failure had not taken place more than 300 years and sometimes 930 years. This classification was useful for evaluating the high risk area for the slope failures.

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