For vibration control of a flexible rotor suspended by active electromagnetic bearings, the PID control is widely used. But the capability of this controller for improving damping properties of the mechanical system is not so good because high order bending modes often become unstable increasing the derivative feedback gain. In this paper the feedback control scheme which uses the external forces estimated by an inverse system is presented. Simulating forced vibrations, it is found out that without the large derivative gain this controller enables to reduce resonance vibrations of a flexible rotor in case of random external forces being operated to the mechanical system. In the experimental system applied above feedback control, measured values of forced vibrations agree with numerical results.