PURPOSE: To realize a stable frequency adjustment by forming a capacitor between the interdigital part of a piezoelectric plate and the conducting film of a thin plate having the same expansion coefficient as the piezoelectric plate and changing the capacity of the capacitor.

CONSTITUTION: A piezoelectric vibrator has an upper surface electrode 102 and a lower surface electrode 103, an upper surface electrode lead part 104 and a lower surface electrode lead part 105 extracted from them, a piezoelectric body 101 where a interdigital part 112 connected to it is vapor-deposited, and a conducting film 122, and a thin plate 121 having the same expansion coefficient as the piezoelectric body 101 is stuck and formed by adhesives 123. The capacitor is formed by the interdigital part 112 vaporized on the lower surface of the piezoelectric body 101 and the conducting film 122 vapor-deposited on the lower surface of the thin plate 121. By cutting the optional place of the interdigital part 112 with a laser light in the upper direction of the piezoelectric body 101, the capacity of the capacitor is changed and the frequency is adjusted.