PURPOSE: To focus an ultrasonic wave irradiated from a piezoelectric body onto a sound axis with a minute and high sound field, by providing an electrode on both sides and the piezoelectric body having ≥2 radii of curvature on both a sound operating side and its opposite side.

CONSTITUTION: The electrodes 121, 122 are formed on both sides of a high polymer piezoelectric film 11 and a copper-made reflecting plate 13 is bonded on the electrode 122. Then, the high polymer piezoelectric film 11 is pressed with a metallic die processed in advance to form the sound operating faces having different radii of curvature. Further, the high polymer piezoelectric film 11 is bonded to a cylindrical box 15 having a step part at the inside of the tip, and leads 14, 14 are connected to the electrodes 121, 122, then a support 16 made of epoxy resin is formed. Moreover, an insulating layer 17 is formed on the surface.