A hub can be displaced between an initial position at which the hub is located on a front end side of an inner cavity of a shield and an inner needle penetrates an outer needle and a retracted position at which the hub is located on a rear end side of the inner cavity of the shield and the inner needle is housed within the inner cavity of the shield. A stopper includes an insertion portion that is inserted into the inner cavity of the shield and a base portion that is located on a rear end of the insertion portion. The base portion includes a roof portion that exposes part of an outer circumferential face of a tube connected to the hub and covers the remainder thereof, and a pair of grasping portions that are arranged to sandwich the tube and can be elastically displaced so as to grip the tube.
