PROBLEM TO BE SOLVED: To provide a melanin-producing cell-growth inhibitor which is natural origin and has high safety as well as an excellent efficacy which inhibits melanocyte proliferation, and to provide an external preparation for skin containing the same.SOLUTION: There is provided a melanin-producing cell-growth inhibitor characterized by containing as an active ingredient Gloiopeltis furcata extract obtained by extracting Cryptonemiales Endocladiaceae Gloiopeltis furcata with alcohol having a water content of 0-45 vol.%. The alcohol is preferred to be one or more monohydric alcohol selected from ethanol, methanol, 1-propanol, isopropyl alcohol, and butanol, or one or more polyhydric alcohol selected from 1,3-butylene glycol, propylene glycol, and glycerol, and is preferred to be high alcoholic content. And there is provided an external preparation for skin characterized by containing the melanin-producing cell-growth inhibitor.
