Many landslides occur in places where landslides had been generated in the past, or in the immediately surrounding area. For prevention and mitigation of landslide damage, it is very important to create landslide inventory maps that show the locations of past landslides. Therefore, the National Research Institute for Earth Science and Disaster Prevention (NIED) in Japan, has published “Landslide Distribution Maps”. These maps include more than 380,000 landslide topographies covering all of Japan, produced by interpretation of aerial photographs. However, the landslide distribution throughout Japan is not balanced ; there are density differences. We propose a method of wide area landslide assessment that uses the features and distributions of a specific geological setting. We calculate the landslide body ratio for each geological unit. This ratio is the rate of the landslide body area in each geological unit to the entire area of that geological unit. The results show that the landslide body ratio differs greatly from one geological unit to the next.