To obtain a new base-isolation effect by adopting an artificial ground structure which enables water to continuously be accumulated in a position immediately below a foundation of a building.

The building 2 is constructed on the foundation 4, and a waterproofing layer 10 is buried in the ground position immediately below the foundation 4. The waterproofing layer 10 has a bottom and a side which is extended from the end of the bottom. When the underground water level rises, water is accumulated inside the side. Even after the underground water level has dropped, water keeps to be accumulated inside the side. Because of the water which keeps to be accumulated, the vibration of the building is reduced at the time of the occurrence of an earthquake.