Determinants of internal migration can be classified into the factors associated with places of origin and destination, those intervening between the place of origin and the place of destination, and those relevant to a migrant himself, or personal factors. Among those factors affecting internal migration the last factor is the most decisive one for an individual movement or change of residence, although it is difficult to be evaluated quantitatively as including psychological factor. In this paper the determinants of various flows of internal migration in Japan are disclosed being based upon the data derived from the Survey on Reasons for Migration, conducted by the Land Agency, covering the all migrants aged 15 years and over between shi, ku, machi and mura, or minor administrative areas in Japan, for July 1980 to June 1981, on the sampling enumeration. According to the analysis of the data, it was found that the most important reason for overall flows of migration for the whole country was "employment", but it covered 39 percent only of the all migrants. Other most significant reasons for migration were those relevant to non-economic factor such as "family's reasons", "marriage", "housing", and "schooling", etc. Also, it was recognized that the personal factors as determinants of migration, measured by the reasons for migration, varied among the migratory flows. For the flows within a major metropolitan area the reason of "housing" was the most important factor. On the other hand, for the flows between major metropolitan areas and for those between a major metropolitan area and non-metropolitan areas, "employment" reason was most influential. For other flows including return migration, "employment" and "family's" were most significant. Further, the analysis by sex and age disclosed that the personal factor as determinants of migration was associated with the stages in life cycle of the individual.
