PURPOSE: To prevent overturning of a structure by absorbing vibration of the ground, by forming a device of a lower base stand plate, an intermediate plate, an upper plate, rolling spheres and assemblies to support these.

CONSTITUTION: An intermediate plate 3 is arranged between a lower base stand plate 2 on the grounding side and an upper plate 4 on which a structure is directly placed. Rolling sphere groups 8 and 5 between the plates 2 and 3 and between the plates 3 and 4 are supported with rolling sphere assemblies 7 and 10. Then, these are formed as a two-stage rolling structure, and the upper and lower sphere groups 5 and 8 rollingly rotate without practically causing frictional resistance, and a base isolation object structure H placed on the upper plate 4 maintains a stationary condition as speed of lateral swinging - reciprocating motion becomes violent. Therefore, base isolation is more reliably attained, and can act effectively to a high degree.