To reduce the quakes due to an earthquake, and to prevent damage by spreading gravel all lover between a building and a reinforced concrete board installed under the building and using the whole as a vibration-isolation foundation.

Recessed reinforced-concrete boards 3 working as a wave- absorbing block are mounted on a ground 1 supporting a building 2. Gravel 5 is spread all over the reinforced-concrete boards 3, push-up preventive boards 6 for gravel 5 are placed, and a foundation pressure-resisting board 7 supporting the building 2 is installed. Cushions 4 using a rubber, etc., which have a durable period and are hardly deteriorated and abound in elasticity, are mounted on both side sections of the foundation pressure-resisting board 7 in order to correspond to the horizontal motion of the building 2. Horizontal and vertical motions as seismic waves from the ground 1 are reduced and a high vibration-isolation effect can be dislayed in spite of low cost by setting up gravel 5 among the foundation pressure-resisting board 7 and the reinforced-concrete boards 3 and holding down the building 2 by the cushions.