To make a damping effect unchangeable even when the direction of vibration applied to a base changes to a right angle by arranging damping materials in a bilaterially symmetrical position separate from the center on a horizontal reference line passing through the center of a shelf and a bilaterally symmetrical position separate from the center on a horizontal directional straight line passing through the center by crossing at a right angle to the reference line.

A shelf 5 is fixed above a base firmly fixed to a floor surface or the like through a damping material 10. This damping material 10 is composed of, for example, sheet metal 2, a spring 3 and sheet metal 4. The damping material 10 is arranged by a set in a bilaterally symmetrical position respectively separate by a specific distance R1 from this central point O on a horizontal directional reference line L1 passing through the central point O of the shelf 5. Another one set is arranged in a bilaterally symmetrical position respectively separate by a specific distance R2 from the central point O on a horizontal directional straight line L2 which crosses at a right angle to the reference line L1 and passes through the central point O. The installing direction of the damping materials 10 is set so that the spring 3 inclines in the outside direction on the reference line L1 or the straight line L2.