This paper aims to clarify the standard shape character of Yato-topography by classifying the small valleys whose small administrative unit name includes “Ya” that means valley. In the case study area, there are most Yato-topography with following characteristics, the reclaimable fields area is about 1 ha, the forest area is about 3 ha, the entrance width of vale is about 60m, and the distance from the entrance to the end is about 200m. This study declares that basic Yato that is social units units have these characteristics. In other words, Yato is a unit that has fields for mainly agriculture, whose area is about 1 ha, have forest as the water source whose area is three times larger than the fields. In the conventional method for extracting ato that uses the stream order, the areas of Yato units varies widely because of the influence by the fractal form of vales. In the method using small administrative unit for extracting Yato, the areas of Yato units are certain. Therefore, it is considered that the method in this paper is more appropriate.
