The present application relates to a polymer and a use thereof. The present application may provide a functional polymer which expresses a low solubility to a polar solvent and a non-polar solvent and which is suitable for forming a film. If applied to the use of cosmetics such as mascara or to medical uses, the polymer in the present application may express a tolerance to diverse solvents such as sebum, sweat, tears and the like, and thus enables makeup to last, etc. Accordingly, the polymer may be applied to diverse uses and used in film forming agents, cosmetic compositions, or cosmetics, or the like.