The subject of present invention is to provide a skin external agent suitable for prevention or improvement of chromatosis. To solve this subject is to provide a prevention or improvement medicament for chromatosis and a skin external agent comprising the said component. The said prevention or improvement medicament for chromatosis is composed of the compounds represented by following general formula (1), isomers and/or pharmacologically acceptable salts thereof, ,[wherein R1represents unsubstituted aromatic group or substituent-containing aromatic group R2represents hydrogen atom, liner or branched alkyl of 1~4 carbon atoms, acyl having alkyl chain of 1~4 carbon atoms R3represents hydrogen atom or liner or branched alkyl of 1~4 carbon atoms].本發明之課題係提供適合色素沉澱之預防或改善的皮膚外用劑。藉由提供一種色素沉澱之預防或改善劑,以及含有該成分的皮膚外用劑而解決本課題,該色素沉澱之預防或改善劑係由下列通式(1)所代表之化合物、其異構物及/或此等之藥理學上可容許的鹽而成:[式中,R1代表未經取代或具有取代基之芳香族基;R2代表氫原子、碳數為1~4之直鏈或分枝之烷基、具有碳數為1~4之直鏈或分枝之烷基鏈的醯基;R3代表氫原子或碳數為1~4之直鏈或分枝之烷基]。
