To provide a building material which is formed of a ligneous material as a base material and whose surface is coated, having excellent bending strength, surface property, and dimensional stability without generation of warp and torsion in spite of its lightness in weight, by heightening specific gravities of only top and rear parts without heightening the whole specific gravity of the base material so as to form hard layers on the top and rear faces.

A ligneous material whose water content is adjusted to be lower than a fiber saturation point is sandwiched in between hot platens, heated and compressed at a temperature lower than a softening point temperature of a cellulose as a crystal component of the ligneous material and higher than a softening point temperature of a non-crystal component in the water content after said adjustment. After releasing of the pressure, it is cooled so as to obtain a ligneous material having densified hard layers 2 on the top and rear faces thereof. With this densified material as a base material 1, a decorative layer 4 and a wear resisting film layer 5 are formed on its top face.