In order to provide a band pass filter for high wavelength which has a wideband, small insertion loss and flat passband and obtains steep attenuation, a plurality of ring filters, in which, an input terminal of a high-frequency signal is provided to an arbitrary point on a line in a microstripline ring resonator having the line with one wavelength at electrical length, an output terminal is provided to a point positioned at a half wavelength at electrical length from the input terminal, a open stub of 1/4 wavelength at electrical length (or 1/2 wavelength short stub) is connected to a point positioned at 1/4 wavelength at electrical length from the input terminal, are connected by cascade connection with attenuation pole frequencies being different.