To provide an air spring - electromagnetic actuator combined type vibration isolator that can keep a vibration-absorbing table horizontal with the capacity of a relatively small electromagnetic actuator even though the center-of-gravity position of a mounted object on the vibration-absorbing table moves in large degree.

A vibration isolator is so constituted that a vibration-absorbing table 10 for placing a mounted object A is suspended by jointly using air springs 11 and an electromagnetic actuator 12. In this case, positioning control is performed by the electromagnetic actuator 12 on the basis of an output signal of a compensating circuit based on a position signal of a displacement sensor, and vibration isolating control is performed on the basis of a speed signal obtained by integrating signals of an acceleration sensor 13. The air springs 11 are provided with pressure control means for supporting four corners of the table 10 with air pressure, and the pressure of each air spring 11 is controlled on the basis of fluctuating load generated in association with the movement of the mounted object A on the vibration-absorbing table 10.