To provide a magnetic bearing control system which enables a positive stop of rotation of a rotor by the motor, in case of failure of an inverter which drives and controls a motor and prevent breakdown of controlled equipment such as the rotor and the control system.

The magnetic bearing control system 1 is composed of a motor drive circuitry 13 provided with an inverter 13a for driving the motor 4 which is controlled by an inverter control circuit (inverter control means) 14 and can generate electricity and an overspeed detection circuitry 17 for detecting a rotational speed of the rotor supported by the magnetic bearings 5 in a non- contact manner and driven rotationally by the motor 4. When the overspeed detection circuit 17 detects that the rotor 3 is rotating with the speed exceeding the previously adjusted setting speed of rotation, an electric switch unit 13c provided in the motor drive circuit 13 conducts switching actions, the inverter 13a is disconnected from the motor 4, the motor 4 is connected to a regenerative circuit 13b, and the magnetic bearings 5 are driven and controlled by using regenerated electric power of the motor 4.