This invention provides an inhibitor for melanin formation, which has excellent and high safety on inhibition of melanin formation.The inhibitor for melanin formation comprises a compound of formula (1) and/or pharmaceutically acceptable slats, provided that clotrimazole is excluded.wherein A1, A2and A3are individually hydrogen atom, optionally substituted aryl, and optionally substituted aromatic heterocyclic group； wherein at least one of A1, A2and A3are selected from the aryl or aromatic heterocyclic group, the sum of carbon number for A1, A2and A3is 6 to 50； besides, the adjacent two aryl or aromatic heterocyclic group are bound by alkyl chain or alkenyl chain or formed a ring while the two or more of A1, A2and A3are the aryl or aromatic heterocyclic group； m is an integral of 0~2； X is a hetero atom, hydrogen atom, or carbon atom； R1and R2are individually hydrogen atom and oxo, provided that one of R1and R2is an oxo, the other group does not exist； R3is hydrogen atom or C1-8 hydrocarnons that partial hydrogen or carbon atom are optionally substituted by hetero atoms, and the amount of R3depends on X, R3is individual while there is more than two R3, or R3and X form a ring while there is more than two R3, or a ring is formed while the end of R3binds to a carbon atom of A1, A2and A3.本發明提供一種黑色素產生抑制作用優異、安全性高的黑色素產生抑制劑。將下述一般式(1)所示之化合物(克氯黴唑除外)及/或該等藥理學上可容許之鹽作為黑色素產生抑制劑。式中、A1、A2及A3係獨立地選自氫原子、可具有取代基之芳基、及可具有取代基之芳香族雜環基，但A1、A2及A3之至少一個係選自該芳基或該芳香族雜環基，A1、A2及A3之合計碳數為6至50，又，A1、A2及A3之2個以上為該芳基或該芳香族雜環基時，鄰近的2個該芳基或該芳香族雜環基係經由烷基鏈或烯基鏈鍵結，亦可進一步形成環；m為0至2之整數；X為雜原子、氫原子或碳原子；R1及R2係獨立地選自氫原子及側氧基，但R1及R2之一基為側氧基時，另一基並不存在；R3係選自氫原子、或一部分之氫原子或碳原子可被雜原子取代之碳數1至8之烴基；R3依照X的數存在，但R3為2個以上時，R3為獨立，又，R3為2個以上時，鄰近的2個R3為互相鍵結，可與X一起形成環，又，R3之末端係鍵結於有A1、A2及A3鍵結的碳原子，亦可形成環。
