This lecture will present the results of excavations at a previously unlooted keyhole- shaped tomb dated to the beginning of the fourth century A.D. Although this tomb is relatively close to Yamato where the central polity of the time was located, and a chief buried in this tomb seems to have been loyal to the highest-ranking chief in Yamato, I hope to discuss the weakness of the central polity in the process of state formation in Japan. While excavations took place at the beginning of the 1990's, their results are still very significant in Japanese archaeology.