Abstract: To provide a stable aqueous surface treating agent for architectural/civil engineering structures, which can impart excellent water repellency and oil repellency (water proofness and oil proofness), antifouling properties, weather resistance and durability thereof to structures made of architectural/civil engineering materials such as stones or concrete, particularly porous materials. The aqueous surface treating agent comprises at least one fluoropolymer (A) selected from a polyfluoroalkyl group-containing poly(meth)acrylate (A1) and a polyfluoroalkyl group-containing polyurethane (A2) in an aqueous medium. The aqueous surface treating agent usually contains a surfactant (B), and preferably contains a silicone (C), and further (D) a silane compound having a hydrolyzable group and/or a partially hydrolyzed condensate of a silane compound having a hydrolyzable group.