This paper examinates the basic concepts and the analytic framework for which the structure, the characteristic and the derectionality of the change of industrial agglomeration of the Japanese auto sector are to be discerned. It is the Japanese type-suppliers system suitable for the integral type architecture of car product that invents the original character of auto sector agglomeration. On the other hand, it is the peculiar factors of the business environment after 1990's that are deepening and changing the characteristic.