An ultrasonic apparatus comprising: a three-terminal ultrasonic transducer including a common electrode, a transmitting electrode, and a receiving electrode independent of the transmitting electrode; a transmitting circuit configured to output a driving signal to the transmitting electrode to cause the ultrasonic transducer to transmit ultrasonic waves; a receiving circuit configured to receive a receive signal from the receiving electrode; and a capacitance measuring circuit electrically connected to the receiving electrode to measure an electrostatic capacitance of the ultrasonic transducer, characterized in that the capacitance measuring circuit includes an alternating-current signal generating circuit configured to generate an alternating-current signal of a reference amplitude having a frequency different from a resonant frequency of the ultrasonic transducer, a reference capacitor (Cref) connected between the alternating-current signal generating circuit and the receiving electrode, an amplitude measuring circuit configured to measure the voltage amplitude of the alternating-current signal at the receiving electrode, a capacitance calculating circuit configured to calculate the electrostatic capacitance of the ultrasonic transducer a switching device configured to enable switching between a first state and a second state, the first state being a state where the alternating-current signal generating circuit and the amplitude measuring circuit are connected without interposition of the reference capacitor (Cref), the second state being a state where the alternating-current signal generating circuit and the amplitude measuring circuit are connected with the reference capacitor (Cref) interposed therebetween; and the capacitance calculating circuit is configured to calculate the electrostatic capacitance of the ultrasonic transducer on the basis of an amplitude measured in the first state by the amplitude measuring circuit and an amplitude measured in the second state by the amplitude measuring circuit. a three-terminal ultrasonic transducer including a common electrode, a transmitting electrode, and a receiving electrode independent of the transmitting electrode; a transmitting circuit configured to output a driving signal to the transmitting electrode to cause the ultrasonic transducer to transmit ultrasonic waves; a receiving circuit configured to receive a receive signal from the receiving electrode; and a capacitance measuring circuit electrically connected to the receiving electrode to measure an electrostatic capacitance of the ultrasonic transducer, characterized in that the capacitance measuring circuit includes an alternating-current signal generating circuit configured to generate an alternating-current signal of a reference amplitude having a frequency different from a resonant frequency of the ultrasonic transducer, a reference capacitor (Cref) connected between the alternating-current signal generating circuit and the receiving electrode, an amplitude measuring circuit configured to measure the voltage amplitude of the alternating-current signal at the receiving electrode, a capacitance calculating circuit configured to calculate the electrostatic capacitance of the ultrasonic transducer a switching device configured to enable switching between a first state and a second state, the first state being a state where the alternating-current signal generating circuit and the amplitude measuring circuit are connected without interposition of the reference capacitor (Cref), the second state being a state where the alternating-current signal generating circuit and the amplitude measuring circuit are connected with the reference capacitor (Cref) interposed therebetween; and the capacitance calculating circuit is configured to calculate the electrostatic capacitance of the ultrasonic transducer on the basis of an amplitude measured in the first state by the amplitude measuring circuit and an amplitude measured in the second state by the amplitude measuring circuit.