PURPOSE: To improve soundproof effect in a positioning table device such as a rectangular coordinate system robot by covering a table with an outer cover which has a slit in 8 direction of a feeding axis, also covering a feed screw with a sectionally U-shaped inner cover, and providing sound absorbing members on the respective covers.

CONSTITUTION: An inner side soundproof cover 11 is arranged on a lower side of a screw shaft 4a so as to surround a total area of the screw shaft in a U- character form with the screw shaft 4a being at a center in the U-character. An outer side soundproof cover 12 having a slit in a feeding axis is stood on a base 1 so as to cover both sides of a positioning table device 100. The outer side soundproof cover 12 is composed of an upper surface soundproof cover 12b and a side surface soundproof cover 12a. Sound absorbing members Q made of sponge on which wave-shaped recessions and projections are formed are provided respectively on an inner surface of the inner side soundproof cover 11 and an inner surface of the outer cover 12. Both sides of the upper surface soundproof cover 12b is bent downward to be lower than an upper end of the side surface soundproof cover 12a. Projection lines 2a of a table 2 are projected upward.