As a countermeasure to the recent increase in heavy rainfall events and rapid urbanization,Paddy Field Dam (PFD) has been practiced in Niigata Prefecture,Japan.The PFD is one of the flood mitigation measures using paddy fields with runoff control devices installed in drainage boxes of paddy field plots.Although the flood mitigation function of the PFD has been proven to be effective by our analyses,the propagation of this measure is not easy due to lack of incentives to the farmers.Therefore,we have been making proposals to found a governmental financial support system as one of the means of promoting voluntarily practice of PFD.For the system to be established,the economic value of PFDs social function needs to be estimated.In this study we attempt to estimate the economic value of the PFD practiced in the five reservoirs.