To obtain an architectural panel which can be used even in a wet environment by a method in which an air flow is directed to one main surface of a plaster board having a pair of fiber sheets held between gypsum layers, an adhesive layer is stuck on the surface, and a foil layer is fixed by pressing and heating.

In a plaster board 11, a pair of fiber sheets (paper layers) 12, 13 is held between gypsum layers 14. A piece of foil is supplied by a roll 15, and an adhesive layer is stuck on a foil layer to complete a foil piece structure. Before the plaster board 11 being supplied to an apparatus 10, the exposed surface of the sheet 12 is cleaned by an air flow to remove loose fibers. After that, the plaster board 11 is supplied to the position between a press roller 18 and a heat transfer roller 19, and the roller 19 is heated. A sheet material 16 is stuck on the layer 12 so that its adhesive contacts the layer 12, to the plaster board 11 which passes between the rollers 18, 19.