This paper describes robust vibration framed structure control with active damping consisting of a displacement sensor and an active mass actuator. An H^∞ controller based on a reduced order structural model is designed to suppress spillover destabilization. Model error is considered multiplicative uncertainty between the reduced order model and the high precision order model. Robust pole assignment is used to alleviate difficulty in controller design. This technique assigns the poles of a closed loop system in a desirable region on a complex plane by introducing affine transformation into the framework of the H^∞ control theory. Experiments of the initial response and frequency response are performed to verify that the controller has robust stability and better control performance.