The characteristics of the Japanese academic structure are examined with attention to the evolution of institutional hierarchy, the closed academic structure, and the effects of the academic structure upon academic research. The evolution of Japan's institutional hierarchy in academics has been tightly related to factors of nationalism, bureaucracy, and degreeocracy. The academic elite, as well as various national elites, were trained and sponsored by the central government, and they have monopolized the posts of professors in their alma maters even after the founding of other imperial universities and national universities. The school from which one comes has been an evaluation criteria rather than achievement or merit. In Japan most market shares are occupied by a few universities; market shares is one of the indexes of academic nepotism. The other index of academic nepotism is the inbreeding ratio. The lack of horizontal mobility is caused by the institutional hierarchy. Academic productivity is high among scholars graduated from universities ranked at the top of the institutional hierarchy, since in the closed academic structure, the graduates of the top universities are in the most advantageous position for placement to research posts. (SW)