During the 20th Century, most part of Japanese paddy fields were transformed to productive efficient allotments by the “Agricultural Land Improvement Projects”. However, the rich biodiversity, which was maintained in traditional paddy field forms with nature-near water supply systems, has led to a loss. In this research, the methodology of sustainable paddy field management which is aimed at balancing “efficient paddy field management” and “ecosystem conservation” was proposed by conducting the following three points. The focused site was Asami district in Matsuzaka city. First, the paddy fields were classified into 3 types according to the introduction of the agricultural land improvement project. Secondly, the differences of biodiversity and labor productivity by farmers among the three types were clarified. Thirdly, the future paddy field management scenarios were proposed and examined by considering a compromise point in this trade-off relationship between biodiversity and labor productivity.
