An ultrasound surgical apparatus includes a handpiece which includes a probe provided with a proximal end portion mechanically coupled to an ultrasound transducer and a distal end portion used for treatment of a living tissue; a drive portion which outputs a drive signal; a detection portion which detects, in the drive signal, a cavitation level signal corresponding to a state of cavitation generated in a calibration solution, based on the drive signal of calibration signal strength corresponding to class information about the handpiece; a condition storage portion which stores calibration information; an output setting portion which sets the vibration strength; and a control portion which controls the drive portion so as to output the drive signal of drive signal strength corresponding to the vibration strength set by the output setting portion, based on the calibration information and the class information.