A resonance frequency can be adjusted by shifting the resonance frequency without reducing an impedance function or a withstanding voltage characteristic against a high frequency noise, when blocking, by using a multiple parallel resonance characteristic of a distributed constant line, the high frequency noise introduced into a power feed line from an electrical member other than a high frequency electrode within a processing vessel. Comb teeth M of a comb-teeth member 114 are inserted into winding gaps of air core coils 104(1) and 104(2). For example, first comb teeth M- having a thickness m- smaller than a standard thickness ts are mainly inserted in an effective zone A in a central portion of the air core coils. Further, in non-effective zones B at both sides or both end portions thereof, second comb teeth M+ having a thickness m+ equal to or larger than the standard thickness ts are arranged.