To effectively attenuate radio wave, at a low cost.

A thin conductor plate 2 like a carbon steel plate is stuck on the surface of magnetic substance 1 like ferrite. When a radio wave absorbent is arranged in the vicinity of a radio wave generating source, permeability of the magnetic substrate 1 is remarkably higher than that of peripheral air, so that magnetic flux at the periphery is converged. When magnetic flux penetrates the thin conductor plate 2, an eddy current (i) is generated, and heat is generated by eddy current loss. As a result, energy of magnetic field of radio wave is consumed as heat, and the radio wave is effectively attenuated.