To provide an electrode forming method which quickly and easily forms electrodes of a dielectric resonator with a little electrode dimension variation, a little gap variation between electrodes and a little wear of cutting tools for forming the electrode.

An inner conductor is provided in an approximately parallelepiped dielectric block having at least an open end face perpendicular to the axis of the inner conductor, an outer conductor is formed on another outer side of the block, a cutting tool is rotated to cut a part of the outer conductor to form circular or arcuate insulation parts into at least one outer side approximately parallel to the axis of the inner conductor, thus forming input/output electrodes.