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: step A) obtaining an adhesive agent layer composition comprising free ropinirole in an amount which results in a content of 5 to 13.2% by mass in an obtained adhesive agent layer; step B) heating the adhesive agent layer composition at a temperature in a range from 50 to 76° C. for 5 minutes to 24 hours; and step C) cooling the heated adhesive agent layer composition to normal temperature at an average rate of temperature drop of 1 to 20° C./hour, thereby obtaining the adhesive agent layer comprising the free ropinirole at a supersaturated concentration in a dissolved form.