PURPOSE: To shift a plate in the horizontal direction by a minute force by connecting a plurality of balls for supporting a floating plate onto the horizontal surface of a base member by a retainer and setting the plate and the retainer at neutral positions by a spring.

CONSTITUTION: A plate 25 is joined by a screw 29 onto a floating plate 24 over a ball 23 rotatably connected by a retainer 22, over the horizontal top surface of a base member 21. The plate 24 is floated-up in the no-load state in which a workpiece is not loaded onto the plate 24 by the action of pushing-up mechanism 31W34, and a gap (h) is generated between the ball 23 and the plate 24. The mechanisms 35W38 for urging the plate 24 to a neutral position is installed onto the member 21, and the mechanisms 35'W38' for urging the retainer 22 to a neutral position are installed. When the workpiece is placed over the plate 24, the ball 23 and the upper surface of the member 21 contact, and the plate 24 can be horizontally shifted by a minute force.