Background, Motivation and Objective When cavitation bubbles collapse, strong shock waves and jets cause cavitation erosion.Ikeda, et al.found that renal calculi can be crushed into small fragments using highintensity focused ultrasound (HIFU) via cavitation erosion.1 However, the crushing rate of this method is much slower than conventional methods such as shock wave lithotripsy (SWL).The control of cavitation bubble behavior is an important factor to improve erosion rate because excessive generation of cavitation bubbles blocks ultrasound propagation to the stone and reduces the erosion rate.In this study, the peak-positive enhanced (PPE) and peak-negative enhanced (PNE) waves are generated by superimposing the second harmonic to fundamental to control cavitation bubbles.