An object of the present invention is to provide a patch preparation having an excellent skin permeability of medicament using an acid additional salt of basic medicament. Provided is a patch preparation comprising a support and an adhesive layer on one surface of the support, wherein the adhesive layer contains a basic medicament, a fatty acid-based ionic liquid, and potassium salts and/or potassium ions. Said potassium salts and/or potassium ions are generated as a result of reaction of an acid addition salt of the basic medicament with a compound capable of generating potassium ion in the adhesive layer.
