A capacitive micromachined ultrasonic transducer (cMUT) is constituted by a plurality of transducer elements comprising plural transducer cells that are mutually connected in parallel and comprises: a silicon substrate a bottom electrode placed on the top surface of the silicon substrate an upper electrode placed opposite to the bottom electrode and apart therefrom by a prescribed air or vacuum a membrane for supporting the bottom electrode and a membrane supporting part for supporting the membrane, wherein the cMUT comprises a third electrode which has an electrical continuity to the bottom electrode and which corresponds to either one of the transducer cells of a prescribed number of the transducer subelement or of the transducer elements, and a fourth electrode which is a ground electrode electrically connected to the bottom electrode.
