PURPOSE: To reduce components for constituting a sample stand and to decrease its cost by fixing an electrode unit for placing a substrate and an electrode periphery formed of Al2O3, quartz or aluminum onto a base plate.

CONSTITUTION: An upper surface of a base plate 11 is coupled to a lower surface of an insulator 12a via In (indium) bonding 14. A substantially disclike conductor 12b is embedded in the insulator 12a, and an electrode unit 12 is formed of the insulator 12a and the conductor 12b. An electrode periphery 13 is brought into close contact with the unit 12, and so arranged as to cover the upper surface of the plate 11. The periphery 13 is formed of a cover 13a and a flange 13b. The periphery 13 is fixed to the plate 11 via a bolt 38a.