PROBLEM TO BE SOLVED: To provide a skin external preparation suitable for prevention or improvement of pigmentation.SOLUTION: A skin external preparation contains 1) a compound represented by the following general formula (1), its optical isomer and/or their pharmacologically acceptable salts, and 2) a component having anti-inflammatory activity. In the formula, Ris an unsubstituted aromatic group or an aromatic group having a substituent, Ris a hydrogen atom, a 1-4C straight-chain or branched-chain alkyl group, or a 1-4C straight-chain or branched-chain acyl group having an alkyl chain, and Ris a hydrogen atom or a 1-4C straight-chain or branched-chain alkyl group.
