PURPOSE:To obtain a coating compound composition forming coating films having water vapor transmission, high luster, waterproofing properties and elasticity as well by blending a solvent type synthetic resin with solvent type colloidal silica. CONSTITUTION:(A) A solvent type synthetic resin obtained by dissolving or dispersing a thermosetting or thermoplastic synthetic resin in an organic solvent such as aliphatic hydrocarbons, aromatic hydrocarbons, ethers or esters is blended with (B) 0.5-5.0wt.% of (preferably 1-3wt.%) organosilica sol whose water is replaced with an organic solvent to give the aimed composition. The composition is combined with an existing plural layer coating compound and a plural layer coating film having elasticity, high luster and water-vapor transmission can be formed.