PURPOSE: To solve a problem wherein a wall decorative material is not adhered at all with a repeelable pressure-sensitive adhesive film and a liq. protective coating such as a strippable paint is not repeelable when the wall decorative material main body is applied with a masking to protect stain caused by a joint compd. during treating the joint for the wall decorative material on the surface of which a remarkable unevenness is formed.

CONSTITUTION: The title method consists of forming an uneven pattern on the surface of a wall decorative material, covering the surface with a repeelable surface protective pressure-sensitive adhesive film with a elongation of 200-600% and pressing the film on the surface of the uneven pattern of the wall decorative material through a sponge plate made of a plastic or a rubber and being flexible and rich in elasticity while the film is heated at a temp. which is the softening temp. or higher and the m.p. or lower.