A device for estimating the sensitivity of a position sensor for a magnetic bearing supporting a rotor, the sensor being capable of measuring the position of the rotor in relation to the magnetic bearing, the magnetic bearing including at least one shaft provided with at least two radially opposite coils. The device includes a control, a current-measuring component, a component for measuring the initial position of the rotor, a component for determining a variation in currents, a component for determining a movement of the rotor, and a component for determining the sensitivity of the sensor, configured to determine the sensitivity of the position sensor based on a movement setpoint and on the value of a movement of the rotor.