PURPOSE: To obtain BPF excellent in cut-off performance, by providing the attenuation pole at the high and/or low frequency side of the passing band.

CONSTITUTION: In the 1/4 wave length resonators 7, 7', several tens of turns of conductor such as polyurethane film copper wire are wound on the bobbin 9 made of the insulator such as resin less in high frequency loss, the both ends of the bobbin are open, and the magnetic core 10 is made of ferrite core for equivalent inductance value adjustment of winding. Thus, since the attenuation pole can be provided at high and/or low frequency side of the passing band, BPF excellent in cut-off performance can be obtained.