Nowadays, ‘self-sustaining’ is emphasized for regional development in Japan, because the autonomy of local government is considered important. To reduce regional disparities, the national government has been subsidizing thousands of self-determined regional developments in small cities and rural areas, instead of directing funds to national capital improvement projects, the common technique of regional development in the past. However, as population outflow toward Tokyo and major cities continues, the ineffectiveness of those regional developments provokes criticism from people living in large cities, and it has diminished the confidence and vitality of small cities and rural areas. This paper suggests that public debate about regional development is needed to foster consensus among citizens. People living in major cities should be involved in this discussion, since they may recognize that the prosperity of Tokyo and major cities is not sustainable without reducing regional disparities. Mutual understanding about the necessity to reduce regional disparities encourages people who live in underdeveloped areas, and is increasingly important for regional development in the era of declining population in Japan.