PURPOSE: To absorb the electromagnetic wave by integrating a lot of corrugated plates having the electric resistance thin films into the cavity section of foaming plastic body with the electric resistance films on the surface and with the cavity section in the inside and converting the electromagnetic wave into heat energy.

CONSTITUTION: A lot of corrugated plates 3 having the electric resistance thin films are integrated into the cavity section of foaming plastic body 2 with the electric resistance films on the surface and with the cavity section in the inside. The plastic body 2 shows a shape of square quadrangular prism. When the electromagnetic wave comes incident from the upside, the plastic body 2 and plates 3 are all overlapped to form the waveguides. Accordingly, the electromagnetic wave is converted into heat energy and it is absorbed.