A method for producing a water/oil repellent composition can produce an article which is excellent in the oil repellency while maintaining the water repellency and the heavy-rain durability. The method includes mixing an emulsion of a polymer having from 10 to 50 mass % of units based on a monomer having a perfluoroalkyl group per all units and an emulsion of a monomer component containing at least 80 mass % of a monomer having a perfluoroalkyl group so that the proportion of the mass of the polymer will be from 50 to 99 mass % per the sum of the mass of the polymer and the total mass of the monomer component and then polymerizing the monomer component. The monomer component includes emulsified particles in the emulsion of the monomer component. The emulsified particles have an average particle size of from 50 to 600 nm.