The researches have been ongoing on various vibration control methods for resonant system. Reflected wave rejection-based vibration control is one of the vibration control for resonant system which considers high order resonances owing to the wave equation. However, the conventional reflected wave rejection-based vibration control mainly focuses on the position control, the torque/force control of the resonant system has not been researched. In this paper, reflected wave rejection-based vibration control is extended to the torque/force control of the resonant system which is modeled as wave equation, and the torque/force control of the resonant system based on a wave-based load disturbance observer is proposed. In the proposed method, the vibration is suppressed by the reflected wave rejection, and torque control is constructed based on an environmental torque estimated by the wave-based load disturbance observer. Additionally, the design procedure of control gains are presented. The validity of the proposed method is confirmed by the experimental results.