According to "Hogen Monogatari" (The Tale of the Hogen War), he was the son of Emperor Seiwa's sixth Imperial Prince Sadazumi, and his mother was Udaijin (minister of the right), MINAMOTO no Yoshiari's daughter.
『保元物語』によれば、清和天皇の第6皇子貞純親王の子で、母は右大臣源能有の娘。