Disclosed is a magnetic bearing system capable of simplifying a demodulation operation and reducing a processing load associated with a magnetic levitation control. A carrier signal having a frequency fc is apply to a sensor through a filter. The sensor operates to modulate the carrier signal, and a difference amplifier operates to calculate a difference between the amplitude-modulated signal F.sub.AM (t) and a sensor reference signal Fstd (t). An A/D converter operates to A/D convert a difference signal Fsub (t) output from the difference amplifier to a discretized sensor signal. In the A/D conversion, a sampling frequency fs is set to satisfy the following relation: fc: fc=nfs or fc=fs/2 (n is a natural number). Thus, the discretized sensor signal includes no carrier wave, and therefore a demodulation operation which has been previously essential can be simplified.