PURPOSE: To simplify a circuit and to reduce the cost thereof by adding a control circuit inputting a commercial power supply signal and modulating the transmission frequency of a voltage control ultrasonic frequency transmission circuit by a commercial frequency or the integer number times thereof to perform sweep transmission.

CONSTITUTION: An ultrasonic generator is constituted of a voltage control ultrasonic frequency oscillation circuit 1, an amplifying circuit 2, a driver filter circuit 3, a power amplifying circuit 4 and an ultrasonic vibrator 6 and a control circuit 7 inputting a commercial power supply signal to modulate the oscillation signal of the power control ultrasonic frequency oscillation circuit 1 by the commercial frequency or the integer number times thereof is added. In the operation circuit 10 of the control circuit 7, a DC voltage signal is biased to modulate a control voltage signal by the commercial frequency signal taken out of a commercial power supply input terminal. Therefore, in the voltage control ultrasonic frequency oscillation circuit to which the oscillation reference voltage signal outputted from the operation circuit 10 is inputted, the sweep transmission of the cycle corresponding to commercial frequency is performed.