PURPOSE: To inexpensively control the movement, to reduce noise and to dispense with maintenance such as greasing by providing a couple of toothed pulleys before and behind the sides of a bench, laying a toothed belt endlessly over the pulleys and driving the pulleys.

CONSTITUTION: An upper face on which a sheet glass W is placed and a thin- layer closed spatial chamber to be supplied with compressed air below the upper face are provided to a bench 1, and many through-holes 8 are scatteringly furnished to the upper face wall, a couple of toothed pulleys 19a and 20a and a couple of toothed pulleys 19b and 20b are provided before and behind the sides 1a and 1b opposed to the bench 1, toothed belts 24a and 24b are laid endlessly over the pulleys, and the ends of a movable body 2 laid between the sides of the bench 1 and freely movable horizontally in the X-axis direction along the sides are fixed to the belts 24a and 24b. The rotation of a single servomotor 25a is transmitted to the pulleys 19a and 19b for driving the belts.