The paper is intended to obtain some empirical findings on domestic labor migration in Japan in its relation to such economic incentives as income level and wage rate, and to develop some economic hypotheses on inter-regional mobility of labor. These informations and hypotheses may be served as a clue to further understanding of the past rapid growth of Japanese economy and have significance for the problems of manpower recruitment and mobilization planning in her future course of development. However, the study does not attempt to project any forthcoming changes in regional mobility of labor.