The present invention provides a water-based adhesive patch which can stably contain only one of the optical isomers, S- and R-isomers, of a drug in a relatively high concentration over a long period and which has excellent tackiness and shape retentivity and, despite this, enables the drug to highly permeate the skin. Specifically, the present invention provides a water-based adhesive patch including a plaster which contains only one of the optical isomers of a drug as an active ingredient.
