PURPOSE: To ensure a vibration space and to facilitate forming of a lead electrode.

CONSTITUTION: A 1st layer 11 is made of an insulation material, has a recessed part 111 open at one side and conductor layers 112, 113 are adhered on ad end face around the recessed part 111. A 2nd layer 12 is made of an insulation material and laminated on the end face of the 1st layer 11 so that the conductor layers 112, 113 are exposed at an inner circumferential side 121 and an outer circumferential side 122. A piezoelectric vibrator 2 has vibration electrodes 22, 23 opposite to each other on both sides of a piezoelectric substrate 21, its thickness d2 is thinner than a thickness d1 of the 2nd layer and they are mounted on an exposed part of the conductor layers 112, 113 placed at the inner circumferential side of the 2nd layer 12 and the vibration electrodes 22, 23 are in continuity with the conductor layers 112, 113.