Abstract: The present invention relates to a stainproof-treating agent which comprises (A) 0.05 to 30 percent by weight of a nonvolatile resin ingredient, (B) 0.05 to 30 percent by weight of a nonvolatile ingredient of at least one oxide sol selected from the group consisting of an aluminum oxide sol, a silica sol, a zirconium oxide sol and an antimony oxide sol, (C) 1 to 50 percent by weight of an organic solvent and (D) 40 to 99 percent by weight of water, wherein the resin of the ingredient (A) has a solubility parameter of 10 or more and is insoluble in water at 25° C., a method for stainproof-treating by using the stainproof-treating agent and a stainproof-treated article obtained by the method for stainproof-treating. The stainproof-treating agent of the present invention can be applied on a substrate without requiring a special device and can provide excellent stain resistance by modifying a substrate surface hydrophilic by a simple work.