PURPOSE: To easily and certainly obtain a resin molded article with good quality without requiring high molding technique and mold accuracy, by forming a protruded rib to the outer edge of the leading end part of a mark part protruded from a back side resin layer in a first cavity while bringing the projection of a second cavity into close contact with said protruded rib to mold a surface side resin layer.

CONSTITUTION: In the recessed mold part formed in the recessed mold part 11 of a first cavity 20, a ring shaped protruded rib 23 is formed to the outer edge of the leading end of a mark part 6 to form a back side resin layer 21. In the next step, the cavity 20 is detached to combine a second cavity 23 with a common core 10 and a protruded part 14 is pressed to the leading end part 7 to collapse the protruded rib 23 under pressure while the outer edge of the protruded part 14 is brought into close contact with the outer edge of the leading end part 7 to hermetically seal the cavity. In this state, a resin material is injected into the space of the core 10 and the second cavity 13 to integrally mold a surface side resin layer 5 on the back side resin layer 21. By this method, burr generation is certainly prevented and a resin molded article with good quality can be easily and certainly obtained without requiring high molding technique and mold accuracy.