An external preparation for skin has a pH value of 2.0-5.0 and comprises: (a) 1.0-7.0 mass % of at least one of the members selected from hydroxy acids, (b) 0-0.1-3.0 mass % of a crosslinked type N,N-dimethylacrylamide-2-acrylamido-2-methylpropane sulfonic acid sodium salt copolymer, and (c) 0-0.1-3.0 mass % of an associating thickener constituted of a compound of the formula (1): R1—{(O—R2)k—OCONH—R3[—NHCOO—(R4—O)n—R5]h}m (1) wherein R1 represents a hydrocarbon group, R2 and R4 represent alkylene groups having 2-4 carbon atoms, which may be identical or different, or a phenylethylene group, R3 represents a hydrocarbon group, which may have a urethane bond, R5 represents a branched chain or secondary hydrocarbon group, m is a number of at least 2, h is a number of at least 1, k is a number within the range of 1-500, and n is a number within the range of 1-200.
