A prefilled syringe outer cylinder (6) is provided with the following: an outer cylinder body (61) a flange part (62) that is disposed on a proximal end of the outer cylinder body (61) , protrudes outward and cannot pass through an outer cylinder holding opening (45) a nozzle part (64) disposed on a distal end of the outer cylinder body (61) and a lock adaptor (70) that covers the nozzle part (64), has a larger diameter than the outer diameter of the outer cylinder body (61) , and can pass through the outer cylinder holding opening (45). The prefilled syringe outer cylinder (6) is inserted into the outer cylinder holding opening (45) of an outer cylinder holding member (4) from the proximal side and the flange part (62) comes into contact with the peripheral edge of the outer cylinder holding opening (45) and enters into a suspended state. Further , the prefilled syringe outer cylinder (6) has an inclination part (72) that is positioned at the proximal end of the lock adaptor (70), is inclined towards the outer peripheral surface of the outer cylinder body (61) , and is for guiding when the prefilled syringe outer cylinder (6) is withdrawn from the outer cylinder holding opening (45).
