A softening agent composition including (1) a silicone polymer, (2) a water-repellent polymer, (3) an emulsifier, and (4) a liquid medium that is water or a mixture of water and an organic solvent. Also disclosed is a method for producing the softening agent composition which includes producing a water-repellent polymer by polymerizing, in the presence of the silicone polymer, a monomer that constitutes the water-repellent polymer. The water-repellent polymer may be at least one selected from the group consisting of fluorine-containing polymers and non-fluorine-containing polymers. Also disclosed is a method for treating a substrate with the softening agent composition and a substrate treated with the softening agent composition.