PURPOSE: To intend the straightness in the feed course of a table by including a nut in a its holder, maintaining the feed direction with a static bearing, maintaining the turning direction of the nut with two supporting blades extending in directions at right angles to each other, and giving the degree of freedom in the deviation direction of a feed screw.

CONSTITUTION: When a feed screw 3 is turned with a feed motor 7, holding blades 11b and 12b included in a nut holder 10 have a nut 12 transmit the axial force to a transfer table 2 via a medium element 11 without turning. If there is deviation of the feed screw 3, the combination of the nut 12 having the degree of freedom in the vertical direction and the medium element 11 having the degree of freedom in the horizontal direction removes the influence of the deviation of the feed screw 3 from the transmission. Any special moment varying the clearance between static pressure bearings maintaining the turning direction so that the straightness of the action of the table 2 can be kept.