Grooves are formed on the connection faces of two dielectric base plates in a dielectric resonator. Internal conductors are provided on the inside faces. Coupling electrodes are formed on another dielectric base plate. These three dielectric base plates are connected so that the coupling electrode effects a capacity connection between the internal conductors. This arrangement permits an earth electrode (e.g., an external conductor) to be formed on almost the full exterior of the dielectric resonator, thereby preventing the reduction of the Qo of the resonator and electromagnetic field leakage.