An ultrasonic cleaning apparatus comprises: a power amplifier for amplifying an amplitude of a signal to supply the signal as power to the ultrasonic oscillator; a phase comparator for obtaining a difference between a phase of a current flowing through the ultrasonic oscillator and a phase of a voltage applied to the ultrasonic oscillator and for generating a voltage in accordance with the phase difference; and a voltage control oscillation device for generating a frequency of the signal in accordance with the voltage generated by the phase comparator and for controlling the frequency so that the phase difference is kept within ±30°, wherein the power supplied to the ultrasonic oscillator is regulated to a range from 1W to 10W, and a difference between a resonance frequency of the ultrasonic oscillator and an anti-resonance frequency thereof is regulated to 1 kHz or more.