PURPOSE: To prevent interference with work by movably forming also a frame itself arranged with a slider so that its moving distance is set to a stroke almost double the length of the frame, and further by retracting the frame from a work position or the like.

CONSTITUTION: A frame 1 is movably arranged to reciprocate on a base 2, and pulleys 3, 4 are rotatably supported with both end parts in the frame 1. A drive wheel 5 connected to the one pulley 3 can be turned through a transmitting belt 6 by a motor 7. A linked running belt 8 fixed to the base 2 is mounted between these pulleys 3, 4, and when the pulley 3 is driven and rotated by the motor 7, the frame 1 is reciprocated relatively to the base 2 along the belt 8 by running opposite to each other of the pulleys 3, 4 and the linked running belt 8. A slider 9 is movably arranged on an upper surface of the frame 1 and secured to the belt 8, and at the time of moving the frame 1, the slider 9 is moved by a stroke double the moving distance of the frame 1.