Abstract
　A large number of landslides have occurred in the Tertiary area at the northern part of Nagano Prefecture. There are 444 landslide danger zones which have been designated by the government for control works. In some of these, major landslides have already occurred, but in others, only minor cracks or groundsubsidence have been obsereved. All of them, however, have shown some symptoms of landslide danger. Landslide risk mapping is performed on the basis of past landslide-related data. Five items that are selected from the viewpoint of topography and geology are evaluated in order to express the basic characteristics of slopes. Based on the data taken from two groups, landslide danger zones and stable slopes, the weight relevant to landslide of each catogory in the 5 items is evaluated quantitatively through the quantification of qualitative data. The distribution of critical slopes on which landslides are likely to occur is shown on a map. How the theory should be applied to landslide risk mapping is discussed through two examples.

*信州大学工学部
Faculty of Engineering, Shinshu University
**信州大学教育学部
Faculty of Education, Shinshu University