Usayama-jo Castle was built by Yoshinari MORI in Shiga County, Omi Province in 1570 by order of Nobunaga ODA, who intended to take control of Lake Biwa and Hokkoku-kaido Road, bracing for the advance of the Asakura clan to the south.
元亀元年（1570年）、朝倉氏の南進に備えるべく、琵琶湖と北国街道の押さえを意図する織田信長に命じられた森可成によって、近江国滋賀郡に築かれた。