To provide an aqueous primer composition which facilitates lowering of odor and speeding up in the surface treatment of inorganic substrates for civil engineering buildings such as a roof, a wall, a floor and a road, is excellent in drying the primer accumulated in a recessed part, suppresses foaming of a coated resin layer of a urethane resin and is further excellent in adhesion to inorganic substrates and effectively preventing a coated resin layer from swelling; to provide a method of surface treatment using the same; and to provide the resultant laminated structure.

The aqueous primer composition comprises (A) a water-dispersible polyisocyanate, (B) water and (C) cement as essential components, and optionally (D) an acrylic resin aqueous dispersion. The method of surface treatment for the inorganic substrates by coating the composition onto the inorganic substrates, and the resultant laminated structure are also provided.