Suwa Tadamasa (諏訪忠誠, June 7, 1821 – February 19, 1898) was the 9th daimyō of Suwa Domain in Shinano Province, Honshū, Japan (modern-day Nagano Prefecture) and hereditary chieftain of the Suwa clan. His courtesy titles before the Meiji restoration were Inaba-no-kami and Jijū, and his Court rank was Junior Fourth Rank, Lower Grade, which was posthumously raised to Third Rank.