In a dielectric material block surrounded by a metal film at least one air hole is provided. Inner faces of the at least one air hole are partly applied with at least one metal film. The at least one air hole is provided for providing coupled distributed lines, which are mutually coupled by electric fields passing partly through the at least one air hole, so as to realize a dielectric band pass filter, which has a small-sized structure and attains high precision and non-alignment of resonant frequency.