To enhance the productivity of a board molded product having a grain-like decorative pattern formed to the design surface thereof and to also well keep the quality of the design surface.

In the method for molding the board molded product, natural fibers are wound around a board base material 30 over both surfaces thereof and, in such a state that a thermoplastic resin material is applied to the natural fibers, the board base material 10, the natural fibers and the thermoplastic resin material are pressed under heating to form a grain pattern to the surface of the board base material 10.