This study presents the development of a dexterity support system for stabilizing operation of pendulum using electromyogram (EMG) as input signal. When muscles a joint is flexed or extended, EMG signals are generated in the muscles. In case of controlling unstable systems by using EMG, unskilled operations might cause serious instability and drastic accident. And it is difficult for beginners to keep the system stable for a long time and to train the operation successively. Thus, to overcome those problems, a support system utilizing the safe manual control is proposed. The effectiveness of the support system for beginners is discussed from the viewpoint of the operation support and the accident avoidance.