An ultrasonic probe (2) comprises a cMUT chip (20), which has a plurality of vibration elements whose electromechanical coupling coefficient or the sensitivity changes depending on a bias voltage, and transmits/receives an ultrasonic wave an acoustic lens (26) provided on the ultrasonic wave radiation side of the cMUT chip (20) a backing layer (22) provided on the back side of the cMUT chip (20) for absorbing propagation of the ultrasonic wave an electric wiring portion (flexible substrate (72)), which is provided from the peripheral portion of the cMUT chip (20) to the side face of the backing layer (22) and has a signal pattern connected with the electrode of the cMUT chip (20) arranged thereon and a housing (ultrasonic probe cover (25)) for containing the cMUT chip (20), the acoustic lens (26), the backing layer (22) and the electric wiring portion (flexible substrate (72)). A ground layer (conductive film (76)) of ground potential is provided on the ultrasonic wave radiation side of the cMUT chip (20).
