PURPOSE: To reduce the manhour by forming a metallic thin film on the rear of the main body.

CONSTITUTION: A radio wave absorber 10 has a metallic thin film directly formed on the rear of a main body 11 of the radio wave absorber 10, that is, a radio wave absorbing material such as a sintered ferrite plate of Ni-Zn ferrite. As the method for forming the metallic thin film 12, a physical vapor deposition method, a chemical vapor deposition method, a method of coating a molten metal, a method of spraying a metal or the like is used. As the material for the metallic thin film 12, generally copper or aluminium is practical from the economical point of view or the like. This allows direct lamination to the body surface of a building or the like, enabling the reduction of the manhour.