To provide a piezoelectric device whose frequency can be raised or lowered.

A piezoelectric device (100) in a first perspective is a piezoelectric device which has a piezoelectric vibrating piece (50) of tuning-fork type housed in a package (PKG). The piezoelectric vibrating piece (50) of tuning-fork type includes a base section (23) formed from piezoelectric material, a pair of vibration arms (21) extending from the base section to a designated direction in parallel thereto, and a frequency adjustment section (26) formed on the tip side of the vibration arms. The package (PKG) includes a first metal film (56) on its inside plane (BT) upon which laser light (L) is irradiated. The frequency adjustment section (26) includes a second metal film (28a) extending in a designated direction and an electrode non-formed section (29a) which extends in a designated direction allowing for laser light to penetrate and has no second metal films formed therein.