Essentially, migration can be divided in to two major categories, voluntary migration and forced/involuntary migrations. Voluntary migration, according to the causes of job, residence (including reunion of family), marriage and education, is divided into four types, labor migration, residential mobility, marriage migration and education migration. On the other hand, the major causes of forced/involuntary migrations include wars, natural disasters, political persecutions, and so on; mainly, the types of forced/involuntary migrations are refugee and displaced person migrations, disaster and environmental refugee migration, political asylum migration, and so on.

     From the establishment of the R.O.C. to 1949, the most considerable interregional migration in mainland China was the involuntary migrations resulting from wars. However, in the area not affected by wars, due to the turmoil situation and lack of materials, it is hard to understand and outline the general condition of labor migration, residential mobility, marriage migration and education migration. Since 1949 to now, the R.O.C. has stayed in Taiwan longer than in mainland China. Except for some small-scale involuntary migrations induced by Korean Conflict and Taiwan Strait Battles in 1950s, most of the migrations in Taiwan since 1949 belong to voluntary migrations. As a result, in the aspect of interregional migration of the R.O.C. in mainland China, the categories of involuntary migrations’ times and spaces will be briefly illustrated, but general migration will not be included in the discussion. The topic of this article mainly focuses on the interregional migration of the R.O.C. in Taiwan. The article illustrates the relation between migration and social development, and employs historical structural approach to integrate existed discoveries and the author’s discoveries from various sources of different times. Resulting from the unique political environment of Taiwan, the article emphasizes on internal and external factors influencing migration and Taiwan’s political and economic competitions with other countries, especially China, Japan and the U.S.

     From the perspective of traditional documents of migration, migration is a mechanism that adjusts labor market. People move from the low-labor-demand region to high-labor-demand region. Furthermore, due to the differences of population structure and the space efficacy, labor migration is considered a process with high selectivity. According to the simple classical theory of wage gap, Hicks deems migration as the result of different wages in different regions. People move from low-waged region to high-waged region, which causes the elevation of wage in the region people moving out and the drop in wage in the region people moving in. The wage gap theory shows that the migration has positive effect on the wage in the destination of migration, but negative effect on the original habituated region. Nevertheless, since 1960s, numberless research has proved, such as Greenwood, that the discrepancy of wages in different regions is a significant factor of migration, but not the most influential cause. Other factors such as employment, environment and education are in fact the most decisive factors. From the perspective of personal decisions, Sjaastad’s human capital approach is the most well-known theory about migration in micro-perception. Human capital approach deems migration as an investment of human capital, and the decision-making of migration is based on cost and effectiveness in the theory of human capital. Only when the effectiveness of migration is greater than the cost does the migration occur. Another famous microcosmic theory about migration is Todaro’s expected income theory, which considers that migration is not resulted from the discrepancy of wages, but from the discrepancy of expected income of city and countryside.

     As a whole, according to Piore’s Theory of Dual Labor Market, migration is caused by the developed countries’ changes in population, social and economic structures, which leads to the changes of social stratification and ideology. Domestic labors become unwilling to accept low-level jobs, so these occupations are taken over by foreign immigrants, which results in interregional migration of international labors. As for Wallerstein’s world systems theory, international migration is considered as the result of entrepreneurs and capitalists’ search for lands, materials, labors and new markets in periphery countries. In the past, capitalism was spread by colonial regimes, but in the present, international corporations are the main force. The development of capitalism leads to the globalization of economy, and the development of international migration often grows simultaneously with that of economy.