PURPOSE: To always enable etching under proper conditions irrespectively of the kind of a member to be etched, by performing etching while changing the etching temperature corresponding with the area to be etched.

CONSTITUTION: Light emitted from a member 7 to be etched (substrate wafer) is detected with a light emission monitor 9 (polychrometer) through a fiber 8. Detected signal is sent to a controller 10, which controls the temperature of a circulater 11 for supplying refrigerant to a wafer setting electrode 71 in order to set the substrate temperature, i.e., etching temperature. By using the above system, Si based material different in the aperture area can be worked in the same suitable plasma conditions while ensuring the proper conditions that the anisotropy shape can be obtained.