The present invention relates to an external preparation for skin comprising a compound, such as centaureidin(5,7-dihydroxy-3,6-dimethoxy-2-(5-hydroxy-4-methoxyphenyl)-4H-1-benzopyran-4-one); 5,7-dihydroxy-3,6,8-trimethoxy-2-(3,4,5-trihydroxyphenyl)-4H-1-benzopyran-4-one; 3,5-diethoxy-6,7-dimethoxy-2-(5-ethoxy-4-methoxyphenyl)-4H-1-benzopyran-4-one; and 5,6-dihydroxy-3,7-dimethoxy-2-(5-hydroxy-2,4-dimethoxyphenyl)-4H-1-benzopyran-4-one; and/or salt thereof and 4-n-butyl resorcinol and/or a salt thereof.The present invention provides an external preparation for skin having a function as a substantial lightening cosmetic that exerts whitening action of inhibiting excessive melanin production and keeping natural-looking whiteness.