An ultrasonic operation apparatus comprises a hand piece accommodating an ultrasonic transducer for generating ultrasonic vibrations, a probe which is connected to the hand piece and to which the ultrasonic vibrations are conveyed, a drive signal generating unit for generating a first drive signal that drives the ultrasonic transducer, and a second drive signal the output level of which is different from the first drive signal and for outputting the generated drive signals to the ultrasonic transducer, an output detecting unit for detecting the output current and the output voltage of the second drive signal to the ultrasonic transducer, and a controlling unit, which controls the operations of the drive signal generating unit based on a phase difference between the output voltage and the output current of the second drive signal, for judging the running state of the probe or the hand piece by determining whether or not a resonance frequency at which the phase difference between the output voltage and the output current becomes almost zero can be detected within a predetermined range.