Shiroishi Castle (白石城, Shiroishi-jō) is a flatland-style Japanese castle in what is now the city of Shiroishi, Miyagi. During the Edo period, it was the castle of the Katakura clan, who were hereditary retainers of the Date clan of Sendai Domain. During the Boshin War, it was also temporarily the headquarters of the Ōuetsu Reppan Dōmei. The castle was also known by the name of Masuda Castle (益岡城, Masuda-jō)