To provide a surface coating method which is used for reinforcing the surface of an inorganic porous material such as calcium sulphate and in which a reinforcing thin film, which is cured very quickly and has excellent dimensional precision and excellent external appearance, can be formed by coating the surface of the inorganic porous material with an -cyanoacrylate composition which is prepared by diluting an -cyanoacrylate compound by a volatile organic solvent and made curable by an active energy ray.

The -cyanoacrylate composition contains as essential components (A) the -cyanoacrylate compound, (B) a metallocene compound of a group-VIII transition metal in the periodic table, which contains an aromatic electron-type ligand, (C) an intramolecular cleavage type photo-radical initiator and (D) the volatile organic solvent. The surface coating method comprises steps of: coating the surface of the inorganic porous material with the -cyanoacrylate composition by an application, immersion or spraying method; and irradiating the coated -cyanoacrylate composition with the active energy ray.