A processing device that performs a process of transmitting and receiving an ultrasonic wave includes an ultrasonic device, a transmitter, a receiver, and a controller. The transmitter is configured to output a driving signal to the ultrasonic device. The ultrasonic device includes a high-frequency ultrasonic element line and a low-frequency ultrasonic element line. The high-frequency ultrasonic element line is configured to arrange a plurality of ultrasonic elements having a resonance characteristic of a first frequency. The low-frequency ultrasonic element line is configured to arrange a plurality of ultrasonic elements having a resonance characteristic of a second frequency. The transmitter is configured to output the driving signal of a sine wave to the high-frequency ultrasonic element line in a first mode. The transmitter is configured to output the driving signal of a square wave to the low-frequency ultrasonic element line in a second mode.
