PURPOSE: To remove high-frequency noise and to prevent the generation of a malfunction in heater control circuits by branching a grounding part from between the heaters for heating the inside of a plasma treatment chamber and the heater control circuits and grounding the same through capacitor elements.

CONSTITUTION: Many disk-shaped plasma electrodes 3 are erected on a wafer boat in the treatment chamber 1 and semiconductor wafers 4 are held in parallel with the surfaces of the respective electrodes 3. Every other sheet of the electrodes 3 are connected to the different polarity sides of a high-frequency power supply device 5 on the outside. A reactive gas is supplied into the chamber through an introducing port 1a and is discharged from a discharge port 1b. The high-frequency power is impressed to the electrodes on the down stream of the reactive gas to generate plasma. The heaters 6a, 6b, 6c are dividedly disposed around the treatment chamber and are respectively independently connected to the heater control circuits 7a, 7b, 7c, by which the calorific values are controlled. The ground wire connecting to a chassis 9 is branched through capacitors 8a, 8b, 8c from between the heaters 6a, 6b, 6c and the control circuits 7a, 7b, 7c.