An ultrasound operation system 1 includes an output transformer Tr, a hand piece 2 including an object to be driven including an ultrasound transducer 2f which is driven by the output transformer Tr and a treatment portion 2e which is connected to the ultrasound transducer 2f to perform treatment of a living tissue by an ultrasound vibration generated in the ultrasound transducer 2f, and a non-inductive resistor R2 which is provided between the output transformer Tr and the ultrasound transducer 2f, and perform regulation of an amplitude of the ultrasound transducer 2f by diverting a current which flows into the ultrasound transducer 2f from the output transformer Tr in accordance with a state of a load exerted on the treatment portion 2e and regulating an amount of a current which flows into the ultrasound transducer 2f.超音波手術システム１は、出力トランスＴｒと、出力トランスＴｒによって駆動される超音波振動子２ｆと、超音波振動子２ｆと連結され超音波振動子２ｆで発生した超音波振動により生体組織の処置を行う処置部２ｅとを含む駆動対象を備えたハンドピース２と、出力トランスＴｒと超音波振動子２ｆとの間に設けられ、かつ、処置部２ｅにかかる負荷状態に応じて出力トランスＴｒから超音波振動子２ｆに流れる電流を分流させて超音波振動子２ｆに流れる電流量を調整することで超音波振動子２ｆの振幅調整を行う無誘導抵抗Ｒ２とを備える。
