PURPOSE: To make possible excitation of vibration mode of (1, 1, 1) by improving the electrode shape of the crystal vibrator.

CONSTITUTION: 8 denotes the thickness-width slip crystal vibrator, and 9, 10 denote the exciting electrodes. Two electrodes are disposed on one main surface and an earth electrode is disposed on the other main surface. The side face 9a of the thickness-width slip vibrator 8 is not perpendicular to the Z-axis and has a certain angle of inclination. Now, when alternating voltages are applied to the electrodes 9, 10, electric fields and displacements are produced in mutually opposite directions, thus realizing the vibration mode of (1, 1, 1).