A method of stabilizing a frequency of a piezoelectric vibration element includes: disposing the piezoelectric vibration element in an atmosphere of a vapor of a ring-shaped dimethylpolysiloxane molecule, the piezoelectric vibration element having a metal layer on a surface of a piezoelectric substrate formed of a thickness slip based piezoelectric material; and making the ring-shaped dimethylpolysiloxane molecule subject to chemical absorption with a surface of the metal layer to form a layer of the ring-shaped dimethylpolysiloxane molecule.