An ultrasound suction system applies an ultrasound driving signal generated by an ultrasound driving signal generating section onto an ultrasound generating section, transmits ultrasound vibration energy to a distal end portion via a vibration transmitting section, and, under observation by an observing section, fragments a treatment target living tissue with the ultrasound vibration energy, sucks fragmented living tissue pieces together with fluid supplied to a surface of the living tissue, and acquires by an image acquiring section an observed image in a state in which the ultrasound vibration energy is given. A control section controls output of the ultrasound driving signal on the basis of a result of comparison with a reference image.
