In a dual-mode bandpass filter (1), a metal film (3) is partially formed one surface (2a) of a dielectric substrate (2) or at a level in the dielectric substrate (2), first and second input/output coupling circuits are coupled to the metal film (3), at least one capacitor (7, 8) is provided to the metal film (3) so that when an input signal is applied from either input/output coupling circuit, two resonant modes generated in the metal film (3) are coupled, and the capacitor (7, 8) is formed by viahole electrodes opposing the metal film (3).