The study of early-modern Japanese political history has witnessed great progress in recent years. This progress includes a deeper understanding of the ranks and offices awarded to samurai. However, in regard to the fundamental facts and dating of samurai appointments to ranks and offices, there are several theories even regarding such an important political figure during the period as Tokugawa Ieyasu, and there are many misunderstandings. In order to create a political history of this age, confirming the facts and dating of Ieyasu's posts and ranks is a pressing issue. In this article I confirm the facts and dates of Ieyasu's ranks and offices, ascertain under what political circumstances they were granted, and furthermore determine their significance. To the extent that Ieyasu was an important political figure. Ieyasu's appointments to ranks and offices are dealt with in general works of history, but fundamental studies have not been sufficiently conducted, and there is no scholarly consensus regarding them. Ieyasu was first appointed governor of Mikawa province, then Sakyō Daibu (Commissioner of the Left Division of the Capital), Jijū (Chamberlain), Ushōshō (Junior Captain of the Palace Guards of the Right), Sachûjō (Middle Captain), Sangi (Consultant), Chûnagon (Middle Counselor), Dainagon (Major Counselor), Naidaijin (Minister of the Center), Udaijin (Minister of the Right), Seiitaishōgun (Babarian-subduing General), and finally Daijōdaijin (Chancellor). This article chiefly analyzes his appointment to the posts of Sakyō Daibu, Chūnagon, Dainagon, and Sadaishō, for which there has no confirmation in the historical record. Ieyasu was appointed Sakyō Daibu shortly after being named governor of Mikawa. In general, when someone was appointed to a new office, thr person would then be known by his new official title, but Ieyasu did not employ the Sakyō Daibu title except in relationship to the imperial court, and even after being appointed Sakyō Daibu continued to use his previous title, governor of Mikawa. This is an example of a unique use of an imperial title. The date of Ieyasu's appointment to the post of Chūnagon has been seen as having been on the fourth day of the tenth month of Tenshō 14 (1586) on the basis of a draft decree in the Nikkō Tōshōgû monjo found in Kugyō bunin, but I have confirmed that the actual date was the fifth day of the eleventh month of the same year and locate its significance within the course of the ceremonial relationship of lord and vassal with Hideyoshi. Furthermore, Ieyasu's adoption of Minamoto clan affiliation is seen within the context of the imperial progress to the Jurakutei, but I make clear that he had used the Minamoto clan name previously during the eighth month of Tenshō 15, and I present new evidence for consideration of this name change. The Ieyasu's appointment to Sadaishō (General of the Left) in Tenshō 15 can only be traced back to the occasion of request by the third Tokugawa shogun, Iemitsu, for reissuance of an oral decree in Shōho 2 (1645), and I clarify that the supposed appointment in Tenshō 15 is not historically accurate. Kasaya Kazuhiko's proposal of the existence of a Tokugawa Shogunate under a Toyotomi regency that is premised on the Ieyasu's appointment as Saidaishō and the arguments surrounding it are thus unsustainable.