To solve such problems that: a thin plywood is not commercialized yet because a liquid chemical agent cannot be injected into a 3-5 mm thin plywood material merely by application since a rotary sliced lauan hardy lets moisture through, wherein the thin plywood primarily uses an imported lauan material which is rotary-sliced to about 1 mm and laminated in three layers; and the thin plywood is hard to put into practical use because the thin plywood deviates in a drying step unlike a plywood of 12 mm or more thickness already in practical use, whose production process includes preparing a thick plywood and putting it into a pressurization container to subject it to decompression and pressurized injection to dry it.

There are many problems in commercializing a roller pressed thick wood since cracks generate in a pressing step despite existence of such a technology. A 1-1.5 mm thin wood run through a roller generates less cracks, and also a cell destruction can be performed uniformly since uniform pressing is possible without distortion. The cell destruction is enhanced by a slight speed difference between upper and lower rollers. In particular, the liquid chemical agent can be injected into a core part of domestic Japan cedar, which hardly lets moisture and air through, since the drying can be made easily by the cell destruction in moisture squeezing-out step and the decompression by heating can be achieved. Moreover, peeling prevention as the plywood is made since deviation and distortion hardly generate as a tension of wood varnishes. Thus, the thin plate run through the roller is suitable as a material for nonflammable plywood and functional plywood.