This study aims to define the mechanism of the formation of a regional segregated area of Korean immigrants to Japan. And furthermore to examine the transformations of the ethnic identity with the change of the times and generations. Kotobuki is korean community formed in Yoseba. Yoseba is the space served as a catchment place of day laborers for jobs regarded as relatively unsdilled. such places generally have a large number of cheap lodging houses(doyagai) for them. With the change of the times, this area has become a place where the labor workers flocked into. koreans also came in with them. kotobuki was formed in Yoseba is a proof that socio-economic conditions influenced ethnic community. And the ehinc solodarity in the community got stronger in proportion to the solidarity tends to change and differs in degree accoding to the different generations of and different immigrant periods of the Koreans.