Vibrations of a rotor supported by a repulsive type passive magnetic bearing is investigated. First, the restoring force of a repulsive type magnetic bearing is calculated numerically considering the influences of magnetical anisotropicities of the inner and outer magnets. Then, this obtained restoring force is appoximated by the power series expression considering the effect of the rotation of inner magnet. The effect of each pattern of magnetical anisotropicities of inner and outer magnets on the occurence of resonance phenomenon is clarified theoretically and experimentally.