To provide a damping material capable of corresponding to the unevenness of a substrate material or the like and made easy to dispose.

This removable alcove is equipped with an alcove finish material 16, the damping material 3 provided in contact with the under surface of the alcove finish material 16, the substrate material 18 provided in contact with the under surface of the damping material 3 and a plurality of support devices 22 for supporting the substrate material 18 so as to separate the same from an alcove slab 20. The damping material 3 is formed of a woody fiberboard of which the average density is 0.85-1.05 g/cm3 and the densities of the upper and rear layers of the woody fiberboard are smaller than the density of the layer 5 including the central part in the thickness direction of the woody fiberboard.