PURPOSE: To reduce the vibration of a device even when the opening and closing operation is carried out at high speed by providing the minor loop of acceleration-compensating system feeding back the actually measured acceleration of a platen as controlled variable.

CONSTITUTION: A clamping device is composed of the top force 8 fitted to a platen 7, the position sensor 9 detecting the actually measured position (y) of the platen 7, the acceleration sensor 21 detecting the actual acceleration (y") of the platen 7 and the controller 10 operating the driving part 20 correspondingly to the actually measured position (y) and actually measured acceleration (y"). The actually measured position (y) is sent to both the first subtractor 12 of the controller 10 and the regulator 14 for toggle gain-compensating command value. The compensating value Kfb.y" is outputted to a second subtractor 17. Since the acceleration (y") of the platen 7 is reduced when delay is compensated for, the damping of the driving part 2 is suppressed.