PURPOSE: To make a force sensing control possible further eliminate an influence of such variation element as the shape change of a work, its dimensional unevenness, stone wearing or the like, by respectively equipping a force-displacement detecting mechanism in the pressing direction of a tool and its polishing direction.

CONSTITUTION: A differential type magnetic resistance element 17, 19 and a magnet 18, 20 are set mutually being opposed to an upper surface of each bear ing block 8, bottom surface of a housing 11, the upper of its swollen part and the bottom surface of a table 15. The displacements in the pressing direction Z of a grinder and in its polishing direction X are detected from output voltage of the differential type magnetic resistance elements 17, 19. In this way, a force sensing control is performed by detecting external force and machining reaction force to be fed back while in machining, further a driving mechanism longitudi nally moves through springs 10, 14. Consequently, an influence by a variation element of the shape change of a work, its dimensional unevenness and stone wearing or the like can be eliminated.