In order to achieve miniaturization without degrading Q of a dielectric filter in the present invention, resonant elements has upper and lower ground electrodes. The upper ground electrode is formed of upper ground electrodes which correspond to wide portions and have no pattern formed on a portion corresponding to narrow portions, and an upper ground electrode which corresponds to the narrow portions and formed higher than the layer of the upper ground electrodes. The lower ground electrode is formed of lower ground electrodes which correspond to the wide portions and have no pattern formed on a portion corresponding to the narrow portions, and a lower ground electrode which corresponds to the narrow portions and formed lower than the layer of the ground electrodes.