He possessed Sasakinosho (Sasaki's estate) in Gamo District, Omi Province; his aunt married FUJIWARA no Hidehira, and he himself took a daughter of MINAMOTO no Tameyoshi to his wife.
近江国蒲生郡佐々木荘を領し、秀義の伯母は藤原秀衡に嫁ぎ、自身は源為義の娘を妻としている。