Provided is a method for improving the retention properties of a compound in the skin, which is effective for prevention of aging or improvement of the skin. An external preparation for the skin in an oil-gel form according to the present invention, which contains (1) a compound represented by general formula (1), an isomer thereof and/or a pharmacologically acceptable salt of the compound or isomer, and (2) a partially crosslinked methyl polysiloxane, enables easy migration of the above-described active ingredient (1) into the skin from the preparation, while enhancing the cutaneous absorption and improving the retention properties in the skin. (In the formula, R1 represents a linear or branched alkyl group having 1-4 carbon atoms and substituted by a carboxyl group, or a linear or branched alkyl group having 1-4 carbon atoms and substituted by a carboxylic acid ester group having an alkyl chain with 1-4 carbon atoms； and each of R2 and R3 independently represents a linear or branched alkyl group having 1-4 carbon atoms).提供一種使對皮膚之老化的預防或是改善有效的化合物之皮膚貯留性提升的方法。本發明之含有1)下述通式(1)所示之化合物、其異構物及/或該等藥理學上所容許之鹽、與2)部分交聯型甲基聚矽氧烷之油質凝膠(oil gel)劑型的皮膚外用劑，係使前述1)之有效成分容易地由製劑中往皮膚移動，且於同時提高皮膚吸收性，使皮膚內貯留性提升。[式中，R1表示經羧基所取代之碳數1~4之直鏈或是分枝的烷基、或經具有碳數1~4之烷鏈的羧酸酯基所取代之碳數1~4之直鏈或是分枝的烷基，R2及R3分別獨立地表示碳數1~4之直鏈或分枝的烷基。]
