Abstract ：
This study theoretically investigates the economy of a small country that exports skilled labor to higher developed countries and simultaneously imports unskilled labor from lower developed countries. Compared with the free immigration case, if this country adopts an optimally controlled immigration policy by imposing income tax on immigrants to maximize national income, skills formation is negatively affected and the number of domestic unskilled workers increases. Moreover, under certain conditions, it can be asserted the counter-intuitive possibility that the wage rate of domestic unskilled workers may decrease but that of skilled workers may increase owing to the restriction of foreign unskilled workers.

Keywords : International migration, Economic integration, Skill formation.