The purpose of the present invention is to improve operability when attaching and detaching an outer circumferential portion and a flange portion of a syringe. The present invention is provided with: a mounting base (10) that includes a receiving surface (11) a clamp (20) that moves in a rotational motion along the receiving surface (11) between a clamped position at which the outer circumferential portion of a syringe (S) can be clamped and an unclamped position at which the outer circumferential portion of the syringe (S) cannot be clamped a rotating cam (44) that is provided so as to move in association with the clamp (20) and rotate in two directions and a clamping member (50) that moves toward and away from the mounting base (10) through engagement with the rotating cam (44). Through engagement with the rotating cam (44) moving in association with the rotation of the clamp (20) toward the clamped position side, the clamping member (50) moves toward the mounting base (10) such that a flange portion (f) of the syringe (S) is clamped in the thickness direction between the mounting base (10) and the clamping member (50), and through engagement with the rotating cam (44) moving in association with the rotation of the clamp (20) toward the unclamped position side, the clamping member (50) moves away from the mounting base (10) such that the flange portion (f) is released.
