PURPOSE: To obtain a high dynamic stability with a greater rigidity and attenuation of external force by detecting the displacement of an object with a pressure and controlling it through a static pressure pilot pad and a control pad corresponding to changes in the clearance due to an external force.

CONSTITUTION: A member 1 to be controlled is held in a holding member 3 through a set clearance with static pressure control pads 8 and 9 and a static pressure pad 10. As the member 1 displaces horizontally by an external force, changes in the pocket pressure of static pressure pilot pads 11 and 12 are detected with pressure detectors 13 and 14 and signals thereof are introduced into a servo valve 7 to apply a working pressure to the static pressure control pads 8 and 9 to balance pressures of the pads 8 and 9 so that clearances on the right and the left equal to return the member 11 to a stable position. Thus, the use of an electric servo ensures a high response and accuracy to compose a displacement control system with a force as operation value thereby affording a high regidity.