PURPOSE: To surely prevent resonance of onboard equipment by providing a weight supported by a buffer means which vibrates at the same frequency as and in opposite phase to the resonance frequency of the onboard equipment and a guide rail for guiding the weight in the direction of vibration, and providing a bearing means between the guide rail and the weight.

CONSTITUTION: In a vibration control device for preventing resonance of a spacecraft 1 and onboard equipment 3, a weight 5 supported on a coil spring 4 is guided in the direction of resonance of the onboard equipment 3 by a direct driven rolling bearing 6 and a guide rail 7. The mathematical model of the vibration system comprises a mass m1 corresponding to the onboard equipment 3, a spring constant K1 of the equipment structure system, the mass m2 of the vibration control device and a spring constant K2 of the vibration control device structure system. When the mass m1 is acted upon by an excitation of PCosωt, the mass m2 of the weight is set such that the characteristic frequency ω2= K21/2/m2 of the m2K2 system equals the excitation frequency ωand then the steady displacement X1, X2 of m1, m2 becomes X1=0 and X2=-P/K2 and the exciting force P balances the spring forces X2, K2, whereby resonance of the onboard equipment 3 can be prevented.