A dielectric filter including a dielectric block having two through bores, an outer conductor covering an outer peripheral surface of the block and one end face of the block, an inner conductor covering an inner periphery of the block, and a pair of input and output electrodes formed on the surface of the block, the other end face of the block being in the form of an open end face having no conductor layer. The pair of input and output electrodes are opposed to each other on one plane, and a dielectric block exposing portion having no conductor layer thereon is formed between the two electrodes. The block is provided in the other end face thereof with one groove dividing the open end face, and an inner surface defining the groove is provided with a conductor layer joined to the outer conductor.