So far, the development of tourist area in Japan had been performed under the name of economic development in the region concerned, but it was the real purpose which tourist-related firms or industries obtain profits from the development. However, we think that it is the purpose of tourist area development policy which increases economic welfare of inhabitants in the area concerned. In this paper, we point out that, applying some basic concepts of economics to the analysis of tourist area development, the impacts of tourism development on inhabitants in the region concerned can vary in accordance with the eoconomic conditions in the area, and also, we demonstrate that if we can use regional gross domestic product as a welfare index of inhabitants, then it is the basic subject of tourist area development policy which improves the impacts of change of tourist density on gross national (or domestic) product in the area.
