A servo motor widely used in robot technology was applied to a mixing operation. Periodic interruption of rotation, upward and downward movement and a co-reverse periodic rotation of the impeller were very effective in the liquid mixing. They were especially effective in the high viscosity liquid using a conventional disk turbine impeller. When the periodic interruption of rotation and the co-reverse periodic rotation were used, they were effective at a higher switch frequency for liquid mixing. The larger moving speed and length were effective. In addition, the mixing performance was improved further by the synergy effect of the combination of the co-reverse periodic rotation and upward and downward movement of impeller. Moreover, the mixing performance was improved from unsteady speed mixing at low Reynolds number.