To obtain a stainproof composition comprising a base resin and an additive for modifying a surface as main components, useful as products to be used in a stain-resistant and hygienic toilet seat of warm water cleaning, a bathroom, a washroom, a toilet and a kitchen.

This stainproof composition comprises (A) 100 pts.wt. of a base resin and (B) 0.01-10 pts.wt. of an additive for modifying a surface, preferably a straight-chain polyether-modified silicone compound being a compound of a polyether and a water-repellent silicone as main components. A hydrophilic part and a water-repellent part are exposed to the surface of the resin in the composition. The component A is preferably an acrylic resin (e.g. an acrylic polyurethane resin, etc.), an epoxy resin or a polyester resin. An epoxy resin obtained by subjecting a polyepoxy compound and a polyol, etc., to a polymerization reaction is used as the epoxy resin. A polyester resin synthesized by a condensation polymerization reaction between a polyol and a polybasic acid can be used as the polyester resin.