Much data of National Census on River Environments has been accumulated. In order to utilize those data for river works, we studied the method of analyzing the characteristic of natural environment at Inagawa River. At first, the river was classified into 9 blocks by the river channel characteristic and the distribution of vegetation and birds. In the next step, 11 types of environment units were classified by combining natural environmental element such as location, flood frequency, soil types. We defined these 11 type as biotope, and we chose some species which prefer each biotope. At last, biotope types in each block were counted. From those results of this analysis, the characteristic of Inagawa River was clarified. And the guideline of the river works could be proposed.
