To provide a low-cost and compact dielectric resonator that can greatly improve the design precision of a resonance frequency and can take a simple structure, and to provide a dielectric filter.

In the dielectric resonator, conductors 5a, 5b are arranged on both the surfaces of a dielectric substrate 1, an opening 4 is formed so that the dielectric substrate is exposed only to the conductor 5a at one side, and a conductor 2a is arranged with a prescribed interval M from the opening. The filter is composed by using a plurality of stages of dielectric resonators, thus reducing costs and size.