PURPOSE: To enable a construction cost to be reduced and to enable an installation space as well to be reduced, by a method wherein an absorber is made of a material in which a polyurethane resin having both radio and acoustic wave absorbing characteristics is impregnated with carbon, and the absorbers thus obtained are provided on a ceiling, sidewalls and the like in a room to construct a radio and acoustic wave anechoic room.

CONSTITUTION: Absorbers 5 are provided on sidewalls 2, a door section 3 and a ceiling section 4 on the indoor side, respectively. With this absorber 5, a material in which a polyurethane resin is impregnated with carbon is formed in a pyramidal shape as a material which can absorb both radio and acoustic waves simultaneously. Since the absorber can absorb both the waves having desired frequencies, experiments as for radio wave characteristics and acoustic wave characteristics can be carried out in one laboratory. As a result, a radio and acoustic wave anechoic room does not require much installation space, and moreover it can be constructed at a low cost.