A method for producing a patch comprising a support layer and an adhesive agent layer arranged on at least one surface of the support layer, the method comprising: a step A of obtaining an adhesive agent layer composition comprising oxybutynin hydrochloride as a drug, an acrylic-based polymer and/or a rubber-based polymer as an adhesive base agent, liquid paraffin, a sterol, an organic acid, and a tackifier; a step B of heating the adhesive agent layer composition at a temperature in a range from 55 to 70° C. for 1 to 24 hours; and a step C of cooling the heated adhesive agent layer composition to a temperature lower than room temperature at an average rate of temperature drop of 1 to 20° C./hour, thereby obtaining the adhesive agent layer comprising the drug at a supersaturated concentration in a dissolved form.