Abstract: A spray-coating process which comprises spraying a rubber-asphalt anionic emulsion having a total solid content of 70% by weight or more and a 1-15% by weight aqueous solution of a polyvalent metal salt almost simultaneously by means of separate airless type spraying machines to continuously contact and mix said emulsion with said aqueous solution in the space between the spraying machine and the surface of a substrate to be coated and on the substrate surface, thereby forming a rubber-asphalt solid layer on the substrate surface. By this process, a rubber-asphalt solid layer having a thickness of 4 mm or more and having a water-proof, moisture-proof or gas-proof characteristics can be formed rapidly on the substrate surface.