A hub (40) housed within an inner cavity (24) of a shield (20) can be displaced from an initial position at which an inner needle (50) penetrates an outer needle (30) and protrudes from a leading end of the outer needle to a retracted position at which the inner needle is housed within the inner cavity of the shield. When a stopper (70) is inserted into the inner cavity of the shield and a leading end thereof is caused to abut against the hub located at the initial position, a rear end portion (71) of the stopper is exposed behind the shield. In a state in which the leading end of the stopper abuts against the hub located at the initial position, the stopper can be pulled out of the shield with one hand, by grasping the rear end portion while pressing a finger against the rear end, or the vicinity thereof, of the shield.
