PURPOSE: To make it possible to use the title apparatus for a pallet exchange system of a machine tool under the optimum condition by installing a driving part to attach and detach a movable part to and from a fixed part and installing a shield part to part the front in every connector block in at least one of the fixed part and the movable part.

CONSTITUTION: A driving part 30 to attach and detach a movable part 20 to and from a fixed part 10 and a shield part 25 is installed to part the front in every connector block 14, 23. The title apparatus can easily be made compact as a whole and reliable by using a supersonic wave motor, which generates low speed high torque with small size, gives stable, proper retaining torque, and can be thinned in an axial direction, as the driving source of the driving part 30. Since each connector block 14, 23 is parted by the shield part 25, electric interference is prevented. The apparatus is thus used in optimum condition in a pallet exchange system of a machine tool which is generally under bad working condition.