The present study focuses on relational population concept. The relational population concept is based on proposals made by activists and journalists. Activists like Takahashi, Saside, Tanaka, and so on, claim that it is not necessary to increase the number of residents for regional revitalization. Following these predecessors, the agronomist Odagiri proposed the relational population concept and theorized it. Odagiri sets concern and involvement as the two axes and emphasizes that attention must be given to relational population which exists in diversified horizons between indifference and residence. Odagiri has been appointed as the supervisor by the Japanese government to review regional policies and population policies. At present, the relational population policy is taken as the key to regional revitalization and demographic policies. The relational population concept consists of the following four points: ①turn attention from the existing residential population concept to the idea of diversified relations with a region; ②the region also try to embrace diversification; ③propose concrete policy targets for the final goal of residential population increase; ④make a criterion for the reevaluation of existing activities for regional revitalization. However, the relational population concept has just been proposed and should be, at least partly, critically reviewed. Firstly, the concept is based on the relation between the country and urban areas. Secondly, the term relation is too broad and ambiguous. Thirdly, the concept may lead to undifferentiated policies in practice.