In a lift-up buckle device, a worm wheel is engaged with a screw drive. When a worm is rotated in a forward direction and causes the screw drive to move downward, the worm moves the worm wheel downward. On the other hand, when the worm is rotated in a reverse direction and causes the screw drive to move upward, the worm moves the worm wheel upward. Consequently, the worm wheel may be stably engaged with the screw drive, and the worm wheel and worm may be stably mated.