An object of the present invention is to provide an aqueous dispersion for use in a cosmetic, which has both the flexibility and hair styling properties (hair set retention properties), and which allows for easily re-styling hair when the hair style once set has been disturbed； and a cosmetic including the same. In the above mentioned aqueous dispersion and the cosmetic, a polyurethane is used, which is obtainable from a polyol component including at least one type of a polyether polyol and a polyester polyol, and a polyvalent isocyanate component, wherein the polyol component includes: a polyether polyol containing as a major component a structural unit derived from a polyalkylene glycol having from 2 to 4 carbon atoms, and having a number average molecular weight of 400 or more and 4,000 or less； or a polyester polyol containing a structural unit derived from at least one type of dicarboxylic acid selected from the group consisting of phthalic acid, isophthalic acid and terephthalic acid.
