Natural disasters caused by concentrated heavy rains and typhoons have occurred in various places, and has made a great impact on social activities and people's lives in recent years in japan. Then the effect on transportation caused by disaster on slope failure is very high. The objective of this study is to investigate factors except for soil rainwater index to be caused slope failure. In this study, geomorphic and geological investigation for factor of slope failure occurred in the area of Lake shikotsu in 2014 is discussed. The three locations, of which two locations sited on Route 453 and one location sited on Goryo Line of prefectural road, slope failure discussing in this study caused by heavy rain in September 2014 were surveyed. And a series of physical testing of soils were performed on various soil samples retrieved at each locations of slope failure. Based on the survey and test results, these slope failure locations are classified by geomorphic and geological pattern, and the factor caused to slope failure was discussed in terms of geotechnical engineering.