Transdermal patch

To provide a hydrous transdermal patch in which the stability of glycol salicylate and the adhesive strength and degree of crosslinking of a formulation have been improved. Provided is a hydrous transdermal patch comprising a support body, an adhesive layer provided on the support body, and a release liner attached to the adhesive layer. The adhesive layer contains a) glycol salicylate, b) an alkyl (meth)acrylic acid ester copolymer, c) a partially neutralized poly(acrylic acid), d) a water-soluble polymer compound including carmellose sodium, e) a wetting agent including glycerin, f) a crosslinking agent, g) hydrochloric acid and h) water. The blending quantity of glycerin in the adhesive layer is more than 15 times and not more than 18 times the blending quantity of glycol salicylate on a mass basis.