To easily obtain a conductor for extending an inner conductor to obtain a wavelength reduction effect in an excellent way.

A conductor 7a (7b) for capacitive coupling and an input output capacitive coupling conductor 8a (8b) are provided in a 1st (2nd) dielectric resonator 1 (2) placed side by side. A conductor for extending inner conductor 9a (9b) is provided on a 1st end face 10a (10b) of a dielectric 3a (3b). A recess 17a (17b) is formed to the dielectric 3a (3b) to obtain the conductor for extending inner conductor 9a (9b), conductive paste is applied to the entire end faces 10a, 10b and baked to form a 1st conductor film and a 2nd conductor film by electric plating is formed. Then the conductors for extending inner conductor 9a, 9b are separated by polishment.