PURPOSE: To make a shape sharp and to make it possible to increase accuracy of size by filling a recess on the rear of a plate body having about a flat and U-shaped section of an aluminum extrusion molding with resin foam.

CONSTITUTION: A plate body 1 is an aluminum extrusion molding, and it has about a flat and U-shaped section with the rear side to open. After that, a recess and projection pattern 4 having a V-shaped bending section on the front plate 1a of the plate body 1 is provided over the length of the plate body 1. Then, resin foam 3 is filled in a recess to open the rear side of the plate body 1. According to the constitution, a sharp shape is formed and, at the same time, the recess and projection pattern 4 can be sharply expressed.