PURPOSE: To improve safety by preventing accidental pricking by a needle point in the remounting of a injection needle on a needle cap concerning a gripper which is used when the needle cap is remounted on the injection needle and then, the parts are separated from a cylinder to discard.

CONSTITUTION: A protection part 11 is formed at one end of a cylindrical shell part 10 having a catching hole 14 inside. The protection part 11 is formed in a shape of a funnel and a needle guide surface 13 is formed on the internal surface thereof. A pinch part 15 is formed at a part of the shell part 10 ad a needle cap 6 inserted and fitted into the catching hole 14 can be grasped securely through the pinch part 15 from the external surface of the shell part. A constricted part 16 is formed on the internal surface of the pinch part 15 to hold the needle cap 6 inserted and fitted securely so that the cap will not slip off with the constricted part 16.