An object of the present invention is to provide a composition for external application that is applied to a part of the skin to more effectively elicit the useful effects of an adenine compound such as adenine, adenosine, and a phosphoric ester of adenosine, and that has long-lasting effects and enhanced skin-moisturizing effects. A gel composition for external application containing an adenine compound such as adenine, adenosine, and a phosphoric ester of adenosine is prepared by using agar as a gelling agent. The gel composition is further prepared in the form of a sheet-like adhesive patch. The gel composition in the form of a sheet-like adhesive patch is kept immersed in an aqueous solution containing the adenine compound.