A dielectric device includes a dielectric substrate, a plurality of resonator units, and first and second terminals. The dielectric substrate has an external conductor film thereon. Each of the resonator units has a hole and an internal conductor provided inside the hole and connecting with the external conductor film. The first terminal is provided on the dielectric substrate and electrically coupled with at least one of the resonator units. The second terminal is provided on the dielectric substrate and electrically coupled with at least another of the resonator units. An intermediate conductor film, which is a part of the external conductor film, is provided between the first and second terminals. The intermediate conductor film has an insulating film thereon.