An electromagnetic wave absorber includes a rectangular plate-shaped part having a surface including a flat space at a center of the plate-shaped part and a plurality of oblong rectangular spaces, surrounding the flat space, on each of which at least one pyramidal or wedge-shaped part having an oblong rectangular bottom face is provided, and the plurality of oblong rectangular spaces of the surface of the plate-shaped part are arranged along inside a perimeter of the plate-shaped part so that a longer side of any one of the plurality of oblong rectangular spaces is adjoining with a shorter side of another of the plurality of oblong rectangular spaces adjacent thereto while leaving the flat space at the center of the plate-shaped part.