In recent years, motions of robot mechanisms have become faster than before to improve the efficiency of tasks. However, mechanical sway caused by high-speed operation produces unstable motion even in a small robot. To maintain its stability in motion, a torque cancelling system (TCS) is developed using a parallel solution scheme of inverse dynamics. It stabilizes mechanical sway caused by quick, rotational motion by accurate calculation of dynamics. In this study, we discuss the use of the TCS in a small toy robot and the verification of its effectiveness.