An ultrasound treatment system applies an ultrasound driving signal generated by an ultrasound driving signal generating section on an ultrasound treatment section, treats a treatment target living tissue with ultrasound vibration under observation by an observing section, and acquires, with an image acquiring section, an observed image of the living tissue being treated. A control section controls, for example, output of the ultrasound driving signal on the basis of a comparison result of the observed image and a reference image of the living tissue in a state in which mist does not occur.
