PURPOSE: To manufacture the water proof artificial woody boards capable of preventing the invasion of water thereinto even if cutting or deep flaws and the like occur during the processing period by mixing a number of woody pieces infiltrated, and then dried, with water repellent into synthetic resin and besides forming them into desired form.

CONSTITUTION: In the liquid of heated and melted water repellent 1, woody pieces 2 are put and infiltrated therewith and thereafter set aside to dry and solidify the water repellent 1 adhered to the surface. Next, a number of woody pieces 2a with dried water repellent 1 are mixed into liquid synthetic resin 3 and injected into a rectangular frame 4 and then the synthetic resin 3 is cured and molded, following this, by removing from the frame 4, a water proof artificial woody board 5 can be obtained. Besides, the molding is preferable that compression molding is conducted by injecting it into a mold 6 in use of a press machine, and in the case of employing thermosetting resin as synthetic resin 3, the molding can be effected in a short time if high temperatured heat is applied thereto during the pressure molding period. And, it is preferable that ones in wax group are employed as the water repellent 1.