An ultrasound surgical apparatus includes: an ultrasound transducer that generates ultrasound vibrations； a driving portion that supplies a driving signal to the ultrasound transducer； a distal end portion that is mechanically coupled with the ultrasound transducer and treats a living tissue through a liquid； a detecting portion that detects a cavitation level signal corresponding to a state of cavitation generated in the liquid by ultrasound vibrations of the distal end portion； and an information acquiring portion that acquires information of the living tissue on the basis of the cavitation level signal.
