Abstract: A method for reducing skin sensitization of an asenapine-containing patch comprising a backing layer and an adhesive agent layer, the method comprising: using an adhesive agent for preparing the adhesive agent layer, the adhesive agent containing free asenapine in a range of 2 to 5% by mass, styrene-isoprene-styrene block copolymer (SIS) in a range of 7 to 18% by mass, polyisobutylene (PIB) in a range of 0.5 to 10% by mass, alicyclic saturated hydrocarbon resin in a range of 30 to 70% by mass, and liquid paraffin in a range of 5 to 10% by mass, relative to a total amount of the adhesive agent; and preparing the asenapine-containing patch whose average cumulative amount of skin permeation of asenapine (24 hours) after applying the asenapine-containing patch to skin of a dorsal scapular region of a 5-week-old Hartley white female guinea pig and holding the asenapine-containing patch with an occlusive dressing for 24 hours is in a range of 90 to 300 ?g/cm2 in terms of free form.