To provide a magnetic bearing device which can be reduced in circuit scale and cost.

A differential signal from a sensor circuit 2B is converted into a digital value by an A/D converter 301, prior to be input to a DSP 307. A sampling frequency at that time is set to be 4/3 times or 4/5 times the frequency of carrier wave. The digitalized differential signal is branched into two signals. One of them is multiplied by a sinusoidal discrete value signal from a sinusoidal discrete value calculating section 320, and the other is multiplied by a cosine discrete value signal from a cosine discrete value calculating section 321. The signals which have been multiplied are respectively filtered by a low-pass filter calculating section 315 and then squared by a square-computation section 322. After that, the respective squared results are added to each other by an addition section 323 and a square root thereof is calculated by a square root calculating section 324. Thereafter, gain offset compensation is carried out. A control signal for an excitation amplifier is generated based on the signal subjected to the gain offset compensation.