This study attempts to examine the contents and characteristics of rural-urban migrants during Japanese colonial rule and after that. The major findings are summarized as follows. First,rural-urban migrants under Japanese Colonial Rule were motivated by the extreme rural poverty because of Japanese Colonial policy implementation. There was not any job opportunities and stimulus on the urban sector. Secondly, during the 1945, 8.15-1960`s, rural-urban migrants were motivate by rural population pressure because of lack of job opportunity due to the stagnation of nonagricultural development. Pushing factor played a major role in acceleration of rural population. Thirdly, after 1960`s rural-urban migrants were motivated and accelerated by the rapid growth of economic development and progress. The contents of the rural population mobility is considered on pulling factors because of expansion of job and employment opportunities due to the prosperous and continuous economic development. Pulling factors have been played a major roles in accelerating the migration of rural population since 1960`s.