An emulsion is obtained from emulsion polymerization of a mixture of (a) 1-50 wt % of a triorganosiloxysilicic acid and (b) 50-99 wt % of an ethylenically unsaturated monomer in the presence of (c) an emulsion stabilizer which is an anionic surfactant, nonionic surfactant or polyvinyl alcohol. The emulsion is used to formulate a cosmetic composition capable of forming, on drying, a film which has water resistance, oil resistance and toughness and is thus effective for preventing makeup deterioration. The cosmetic composition containing the emulsion is useful as eyeliner, mascara, eyebrow color, liquid foundation or milky lotion.
