Abstract: A multiple-mode dielectric resonator in which a through hole is formed in a substantially cubic dielectric core so as to pass through opposing surfaces thereof. A conductive support bar is inserted into the through hole. Both ends of the support bar are secured to a cavity, and opposing inside walls defining the cavity are electrically connected to each other (are short-circuited) by the support bar. Therefore, the dielectric core is disposed in the cavity without using a support base, so that the resonance frequencies of TM01 delta modes, which are spurious modes, are considerably separated from frequencies of TE01 delta modes that are used.