A piezoelectric resonator includes a substrate and a thin-film section. The thin-film section includes a first thin-film section supported by the substrate, and an acoustically-isolated second thin-film section which is separated from the substrate. In the second thin-film section, first and second electrodes are arranged on the respective main surfaces of a piezoelectric film, and a vibration section is provided at an area where the first and the second electrodes overlap each other on the second thin-film section when viewed through in the film-thickness direction. The thin-film section further includes a heat-radiating film which is in contact with peripheral edges of at least the first electrode among the first and second electrodes defining portions of a periphery of the vibration section, and which extends from the peripheral edges to the first thin-film section when viewed through in the film-thickness direction.