This paper is concerned with the vibration control of multi-layer structure for ultra-tall buildings and main tower of large bridge etc. We have modeled the multi-layer structure with the distributed mass system as the lumped mass system of two-degree-of-freedom structure and made experimental equipment. The $H_infty$control theory was applied to the design of the control system. The designed control system was simulated by computer. As a result, the designed $H_infty$controller showed the good vibration control performance to impulse response and frequency response.