PURPOSE: To produce wood flour, whose fibrous tissues are broken, at a low cost and in large quantities by heating and compressing the fibrous structure of wood or its bark.

CONSTITUTION: Wood or its bark is pulverized to make sawdust A, and this sawdust A is then compressed under heating to make a wood briquet B. By pulverizing the wood briquet B to break its fibrous tissues, desired wood flour C to which heating-and pressing treatment has been applied is obtained.