PURPOSE: To generate absolute isolation of vibration even for a large displacement by forming a vibration isolating device from a roller dolly, a means to generate long cyclic period for supporting the structure concerned on the dolly, the first actuator furnished between the dolly and the ground, and the second actuator installed between the structure and dolly.

CONSTITUTION: When a ground 2 makes earth motion displacement y1 owing to occurrence of an earthquake, an actuator 7 receives signal from an earthquake sensor 10 and makes displacement control of a roller dolly 3 by a displacement y2 in the direction opposite the earth motion displacement. This dolly displacement y2 generates the remaining difference y=y1-y2 because a static friction and a dynamic friction arise as the frictional resistance of a sliding device 6. The relative displacement y of the dolly 3 with the structure concerned 5 is calculated by a calculating device 13 on the basis of signals given by a dolly sensor 11 and a structure vibrating condition sensor 12. Receiving the result therefrom, an actuator 8 makes displacement control in the direction opposite the displacement of the structure 5 through a resilience means 9. Because the relative displacement y is comparatively small, even a conventional absolute vibration isolating system can satisfactorily put the structure 5 at standstill upon the absolute coordinates.