PURPOSE: To prevent the height of the table from varying by providing a drive control circuit which drives the actuators so that the height variation amount becomes smaller in accordance with the table positions detected by the position detectors according to the data stored in a memory.

CONSTITUTION: An X-table 20 is driven in an X-direction by a variable-speed motor 21 and a feed screw mechanism 22, and similarly, a Y-table 30 is driven in a Y-direction by a variable-speed motor 31 and a feed screw mechanism 32. And, the moving positions of the respective tables 20, 30 are detected by an X-position encoder 23 and a Y-position encoder 33, respectively, and supplied to a drive circuit 60. Also, on the Y-table 30, a table 50 on which a sample such as a wafer is to be mounted is placed through three actuators 41, 42, 43 which expand and contract according to the applied voltage. On the other hand, the drive control circuit 60 applies a drive voltage to the actuators 41, 42, 43 on the basis of the inputted position information and the correction data which was previously stored in a memory 70. Therefore, the height variation on the surface of the table 50 becomes very small.