To improve vibration damping characteristics by calculating physical parameters of a mechanical spring for supporting a vibration resistant body and a viscous element on the basis of a calculating means for the simple physical parameter in which arbitrariness is eliminated and setting a compensating parameter of a floor vibration feedforward compensator on the basis of the calculated value.

While a signal is output from an oscillator 14, an electronic switch 16a for interrupting a signal of a feedback device 12, and a switch 16b for interrupting a signal of a feedforward device 23 are opened by a control signal 15. A vibration compensating stand 1 is vibrated by exciting a power amplifier 7 by the output of the oscillator 14, the outputs of a pre-filter 5 and the oscillator 14 in the exiting period are guided to a physical parameter calculating means 17, and a compensating parameter of a floor vibration feedforward compensator 11 is set by a compensating parameter setting means 18 on the basis of the calculated value. After setting, damping is applied by the operation of the feedback device 12, simultaneously, the feedforward device 23 functions, and the vibration resistant ratio can be improved.