To provide a cylindrical cavity resonator type filter which improves attenuating characteristics of a frequency band which is slightly higher than a passing band.

In the cylindrical cavity resonator type filter, a plurality of the cylindrical cavity resonators 1, in which open windows are formed to the input end and the output end for electromagnetic waves, are mutually connected via a hole part of a coupling plate 6b through the open window formed to its own flange 11 and the open window formed to a flange 11 of the other cylindrical cavity resonator. A conductive member is mounted to the open window of each cylindrical cavity resonator 1. The conductive member does not substantially affect the resonance frequency in a basic mode compared with the state before mounting it. It only enhances the resonance frequency in a high-order mode.