To provide a base isolation device that has a sufficient bearing force against weight while having a simple structure and whose vibration is quickly stopped if the quake of an earthquake stops.

The base isolation device has a support base 2 freely movably placed on an almost horizontal floor 1, a rolling member 2d for freely movably supporting the support base 2 on the floor 1, a first rotating member 3 freely rotatably and pivotally supported to a shaft member 3a provided on the floor, a second rotating member 4 freely rotatably and pivotally supported to a shaft member 4a provided on the support base 2, and an elastic member 5 with one end freely rotatably engaged with the first rotating member 3 and the other end freely rotatably engaged with the second rotating member 4. A rotary shaft 5a at the end of the elastic member 5 and a center shaft 3a or 4a being the rotation center of the first rotating member 3 or the second rotating member 4 are horizontally separated from each other.