PURPOSE: To improve flame retardancy, the tensile strength, and the decorative properties of a wall surface and a columnar surface by a method wherein a cured substance is integrally formed with a fibre sheet down to a depth being a given percentage or more of the thickness of the fiber sheet by a cured body of a mixture of anhydroraulic and/or hydraulic inorganic powdery material and a water emulsion and a fiber sheet.

CONSTITUTION: A mixture of an anhydraulic and/or hydraulic inorganic powder material and a water emulsion is cured down to a depth being 50% or more, preferably 70% or more, of the thickness of a fibre sheet, further preferably throughout the whole of the thickness of the fibre sheet in a state to be impregnated with the fibre sheet, and is formed integrally with the fiber sheet. The whole of the thickness of the fibre sheet is impregnated with the mixture of the inorganic powder material and the water emulsion. Further, the surface thereof is coated with a substance wherein a fibrous substance is mixed in the mixture. An integrally formed layer 1 of the mixture of the inorganic powdery material and the water emulsion and a fiber sheet and a cured substance layer 2 of the mixture of the inorganic powdery material, the water emulsion, and the fibrous substance are laminated together.