PROBLEM TO BE SOLVED: To provide a tyrosinase inhibitor containing undecylenic acid or salt or derivative thereof as an active component and to provide an external preparation including the tyrosinase inhibitor.SOLUTION: The tyrosinase inhibitor comprises undecylenic acid represented by general formula (20) [wherein Rb is H or a saccharide residue from which one hydroxy group is removed] or its salts or ester derivatives, and an external preparation including the tyrosinase inhibitor are provided.COPYRIGHT: (C)2008,JPO&INPIT【課題】ウンデシレン酸またはその塩、或いはその誘導体を有効成分とするチロシナーゼ阻害剤、又該チロシナーゼ阻害剤を含有する外用剤を提供すること。【解決手段】下記一般式(20)[式中、Rbは水素または一個の水酸基を除いた糖残基を示す。]で表されるウンデシレン酸またはその塩あるいはそのエステル誘導体からなるチロシナーゼ阻害剤及び前記チロシナーゼ阻害剤を含む外用剤。【選択図】図1
