A vibration characteristic measuring apparatus includes a magnetic bearing that generates magnetic force on the rotating body of a multi-stage centrifugal compressor, a displacement sensor that measures the vibration amplitude of the rotating body, a current amplifier that supplies a current to the magnetic bearing, and an excitation controller which outputs an excitation control signal for applying vibration to the rotating body and which measures the response characteristics of the vibration of the rotating body to the excitation control signal. The excitation controller outputs a rotating body control signal obtained by adding a vibration eliminating signal for eliminating unbalance vibration of the rotating body to the excitation control signal when measuring the response characteristics, and the current amplifier supplies a current that generates magnetic force in accordance with the rotating body control signal to the magnetic bearing.