This paper presents a controller design approach for load devices to provide robust properties against variations in resonant frequencies and disturbance forces in the mechanism. In the device, a pneumatic actuator and a voice coil motor are combined as a dual-stage to expand the servo bandwidth of the load control. The control performance, however, is deteriorated by disturbances due to the interference force between the actuators as well as the frequency variation in the mechanical resonance. In this research, therefore, a robust controller is designed by PQ method and H∞ control framework against the disturbances of the dual-stage actuator. Effectiveness of the proposed approach has been verified by frequency analyses and experiments using an actual load device.