In a dielectric block, an array of three excitation holes, in each of which one opening is a short-circuited end and the other opening is an open-circuited end, are disposed so as to be interdigitally coupled and balanced input-output terminals are provided at the opening of the excitation holes at both ends of the array. A resonator hole is provided so as to be coupled to one excitation hole of the excitation holes at either end of the array. Thus, a compact dielectric filter with balanced input-output terminals is constructed.