PURPOSE: To manage with one kind of an upper clamp member without damaging a cut material even if the diameter of the material is large, by conducting the cantilever fitting of plate springs which butt against the lower surface of the upper member at the time of push-pressing, at smaller intervals than the pitches of recessed portions.

CONSTITUTION: In the case of cut materials W being clamped, an upper clamp member 2 is moved down to a lower clamp member 1 by operating a cylinder 5, and cut materials W are push-pressed at it lower position. At this time of push-pressing, plate springs 11 which are positioned opposingly against cut materials W, are butted against cut materials W which are positioned at the V grooves 3 of the lower clamp member 1, and compressed. when clamping is released, compressed plate springs 11 are restored to a pre-compression state again, and prepared for clamping the next materials W. Thus, as cantilever plate springs 11 are used, the deformation difference of cut materials W is absorbed, and a great compression quantity is obtained, and also, there is no fear of materials W being damaged.