On December 16, 1180, he raised an army along with his older brother Yoshitsune YAMAMOTO in Seta and Noji in the Omi Province, conforming the rises of Seiwa-Genji (Minamoto clan) in various provinces.
治承4年（1180年）11月21日、諸国の清和源氏の旗上に同調して、兄の山本義経とともに近江国の勢多・野路で挙兵。