When Sadaijin (Minister of the left) ISONOKAMI no Maro died in 717, Prince Nagaya was assigned to Dainagon (chief councilor of state) from Hisangi (advisor at large) at once, which was the highest ranking position among Daijokan (Grand Council of State) after udaijin (minister of the right) FUJIWARA no Fuhito.
霊亀3年（717年）左大臣石上麻呂が死去すると、翌年長屋王は非参議から一挙に大納言に任ぜられ、太政官で右大臣藤原不比等に次ぐ地位を占める。