An ultrasound operation system includes an output transformer, a hand piece including an object to be driven including an ultrasound transducer which is driven by the output transformer and a treatment portion which is connected to the ultrasound transducer to perform treatment of a living tissue by an ultrasound vibration generated in the ultrasound transducer, and an amplitude regulating portion which is provided between the output transformer and the object to be driven, and perform regulation of an amplitude of the ultrasound transducer by diverting a current which flows into the ultrasound transducer from the output transformer in accordance with a state of a load exerted on the treatment portion and regulating an amount of a current which flows into the ultrasound transducer.
