Toshinari was kotaigo gu no daibu (Master of the Empress Dowager's Household) and kotaigo-gu (the Empress Dowager) was called Choshu-gu, thus this collection was called Choshueiso.
俊成が皇太后宮大夫であったので、皇太后宮を長秋宮というのにちなんで命名。