PURPOSE: To provide a wide-band energy shut-in type piezoelectric resonator which can be used in the kHz band by connecting resonance parts, which resonate with about the same frequency as a piezoelectric resonance unit, to the piezoelectric resonance unit through oscillation transmission parts.

CONSTITUTION: When an AC voltage is applied between terminal electrodes 28a and 28b, namely, electrodes 22a and 22b, a piezoelectric resonance unit 22 is oscillated in the longitudinal oscillation mode by expansion and contraction. This oscillation is transmitted to resonance parts 24 and 30, which resonate with about the same frequency as the piezoelectric resonance unit 22, through oscillation transmission parts 23 and 29. Displacement vectors in oscillation transmission parts 23 and 29 and those in resonance parts 24 and 30 are cancelled by each other, and the oscillation is scarecely leaked to the side of connection levers 25 and 31. Consequently, the oscillation energy is shut in parts to resonance parts 24 and 30. An energy shut-in type piezoelectric resonator 21 utilizing the longitudinal oscillation mode is realized when holding parts 26 and 32 are used to externally mechanically fix the piezoelectric resonance unit.