An ultrasonic device is configured to transmit ultrasonic waves and includes a substrate, a diaphragm, a piezoelectric member and a control unit. The substrate has an opening. The diaphragm covers the opening of the substrate. The piezoelectric member is coupled to the diaphragm, and includes a first piezoelectric part and a second piezoelectric part. The control unit controls a voltage applied to the first piezoelectric part to be a vibration voltage and controls a voltage applied to the second piezoelectric part to be a constant voltage when the ultrasonic device transmits the ultrasonic waves.