PURPOSE: To monitor that a prescribed voltage is applied to an electrode or not by a method wherein a specimen attracting electrode provided as buried in a specimen pad is connected to an applied-voltage measuring terminal.

CONSTITUTION: A specimen attracting tungsten electrode 3a is provided as buried in a specimen pad 3 on which a specimen 11 is placed. The tungsten electrode 3a is connected to an applied voltage lead-in terminal 8 and an applied voltage measuring terminal 4 by prescribed two different points located on the electrode 3a. The applied voltage measuring terminal 4 is connected to a comparator 6 and the applied voltage lead-in terminal 8 through the intermediary of a cable 7a. The comparator 6 is connected to the applied voltage measuring terminal 4, an alarming device 10, and a drive mechanism 9 through the intermediary of a feedback signal line 6a, and the drive mechanism 9 is connected to an applied voltage power source 7 and various other equipment which form a parallel plate etching device 100. By this setup, it is can be monitored that a prescribed voltage is applied or not.