An external preparation for skin containing an alkylresorcinol and being excellent in temperature stability (especially high-temperature stability) and photostability. More particularly an external preparation for skin comprising (a) from 0.01 to 5% by mass of 4-isobutyl resorcinol or a salt thereof, and (b) from 0.01 to 5% by mass of one or more selected from L-ascorbic acid or a salt thereof and a 3-O-alkyl-L-ascorbic acid or a salt thereof. If desired, (c) one or more compounds selected from (c-1) a sterol skeleton-having compound (e.g., POE phytosterols, POE cholestanols), (c-2) a vitamin E derivative, (c-3) a compound such as polyglycerin fatty acid esters, polyoxybutene-polyglycerin alkyl ethers, sucrose fatty acid esters, and (c-4) a sorbitan skeleton-having compound may be incorporated in the preparation.
