PURPOSE: To attain miniaturization without deteriorating the characteristic by forming one side of electrodes opposite to each other up to the end of a rectangular substrate.

CONSTITUTION: Opposite electrodes 2a, 2b stimulating energy confinement type thickness longitudinal vibration are provided to the surface of a rectangular substrate 1 made of a ceramic forming piezoelectric resonator. At least one side of the rectangular electrode in the overlapped parts of the electrodes 2a, 2b is formed so as to reach an end of the substrate 1. Thus, non-electrode part is formed only in the longitudinal wave direction and a width W of the substrate 1 in the displacement direction as to a lateral wave is formed so as to form a standing wave and the basic mode of the energy confinement thickness longitudinal vibration is effectively used to form the piezoelectric resonator in a small size without deteriorating the characteristic.