Although he was the third son of MINAMOTO no Michichika, who held the title of Naidaijin (minister of the center), he was acknowledged as the heir after his elder maternal half-sister, MINAMOTO no Zaishi, gave birth to Emperor Tsuchimikado.
内大臣源通親の3男であるが、異父姉である源在子が土御門天皇を生んだために嫡男となった。