PURPOSE: To obtain easily a product of an oscillator in several hundreds kHz band by containing a piezoelectric element polarized lengthwise and provided with an electrode at both end faces in the lengthwise direction into a case having a through hole.

CONSTITUTION: A cylindrical piezoelectric ceramic 9 constitutes a piezoelectric element 11 polarized lengthwise and provided with electrodes 10, 10 at both end faces in the lengthwise direction. The piezoelectric element 11 is contained in a case 13 provided with a cylindrical through hole 12 and caps 14, 14 made of a material are fitted to both sides of the aperture of the case 13. Thus, the cap 14 is fixed to the case 13 while the inner face of the caps 14, 14 is contacted.