PURPOSE: To eliminate a printing stage and to save labor in operations by simultaneously printing a frame work and display numbers with offset ink on the surface of a water resistant resin film having excellent opacity and whiteness and sticking this film via an adhesive to plywood.

CONSTITUTION: The framework and the display numbers are simultaneous printed with the offset ink on the surface of the water resistant resin film having ≥90% opacity (JIS-P 8138) and ≥90% whiteness (JIS-L 1074) and the plywood is stuck by the adhesive to the surface of the printed resin film on the side opposite from the printed surface. Such water resistant resin film is more specifically formed of a microporous film of a biaxially oriented resin contg. fine inorg. powder or a oriented resin film of a multilayered structure formed by using this microporous film of the biaxially oriented film as a core layer and laminating the microporous film of the unaxially oriented resin contg. the fine inorg. powder on one or both surfaces thereof. The stretching or shrinking of the paper by rain water is obviated in this way and the production process is shortened.