PURPOSE: To simplify and facilitate the constitution and manufacture and to improve the electric characteristic by providing a common coupling probe to a guide wall in a way that its axial direction has an angle difference of 45° with respect to each electric field vector of H and V modes thereby using it as the common coupling element.

CONSTITUTION: A circular waveguide resonator main body 1 is provided with 1st and 2nd coupling elements exciting the modes H and V of different frequency from each other individually and the common coupling element is formed by the probe 2 whose axial direction has an angle difference of 45° from each electric vector of the modes H and V respectively. The common coupling probe 2 couples with the modes H and V and acts like a band-pass filter to each of the two waves. Thus, the structure and manufacture are simplified and facilitated and the suitable band-pass filter as the component is obtained.