For obtaining uniformity of processing by controlling difference in impedance between a plurality of processing chambers, in a plasma processing apparatus, a conductor 7 of an attachment portion 3a and a conductor 7 of an attachment portion 3c are connected via a small width portion 7a, and therefore belt-like electrodes 11 and 13 are equal to each other in electrical potential. The visor is formed by a surface generated by revolution having an axis of revolution parallel to the ocular axis and substantially contained in the sagittal plane of the pilot, at the level of the forehead. That is, to exit the high frequency mode that produced the high frequency digital data in the first instance without having to connect a CRT, reboot, or the like. This converts a frequency of the output signal to a desired frequency at or near DC.