was a daimyà  in mid-Edo period Japan, who ruled Yokosuka Domain in Tà Âtà Âmi Province.
Tadamitsu was the second son of Kyà Âgoku Takatoyo, daimyà  of Marugame Domain in Sanuki Province. As Nishio Tadanao, had no heirs, he adopted his nephew in 1729. In 1731, Tadamitsu received the courtesy title of Mondo no Shà  (主水æ£) along with junior 5th court rank, lower grade (ju go i no ge å¾ÂäºÂä½Âä¸Â). Tadamitsu became head of the Nishio clan in 1760, on Tadanao's death, and was appointed Sà Âshaban (master of ceremonies) in the administration of the Tokugawa shogunate. He retired in 1782, and was succeeded by his son Tadayuki.
Tadamitsu died in Edo in 1789, at age 74. His grave is located at the Nishio clan temple of Ryumin-ji in modern Kakegawa, Shizuoka.