The ultrasonic sensor includes, on the same substrate, transmitter elements, receiver elements, a potential controller for receiver electrodes of the receiver elements, and a connection switching unit for the receiver electrodes and the potential controller. During the ultrasound transmission period of the transmitter elements, the connection switching unit connects the potential controller and one of the receiver electrodes, and connects the receiver electrodes. During the reception period of the receiver elements, the connection switching unit disconnects the potential controller and the one of the receiver electrodes, and disconnects the receiver electrodes.
