PURPOSE: To ensure the prevention of occurrence of puncture phenomena and to improve productivity, by forming recessed parts or pierced parts in a substrate in advance, and providing air exhausting paths, which are communicated to said recessed parts or pierced parts and to free air at the positions facing said recessed parts piercing parts.

CONSTITUTION: A decorating step part 1 is provided at the peripheral part of the surface of a wooden fiber plate. Pierced parts 2 and 2, which pierce the substrate to the back surface and can be used as handle attaching holes, are provided at the center of the surface. Recessed parts 3 and 3, which can be used as side plate attaching dowel holes, are formed at the side parts of the back surface. A recessed part 4, which can be used as a bottom plate attaching groove, is formed. Thus the substrate 5 is formed. Meanwhile, the air exhausting paths 7 and 7', which are communicated to the recessed parts 3 and 4 and the pierced parts 2 and to the free air, are provided at the positions of a die member 6 having recessed and projected parts in a fine grained pattern on the entire surface, so that the position face the recessed parts 3 and 4 and the pierced parts 2. The air exhausting path 7 is communicated to the die member 6 and also at spaces 10.