A fluorine-containing copolymer comprising 20 to 60% by mole of the fluoroolefin unit (1), 5 to 45% by mole of the .beta.-methyl substituted .alpha.-olefin unit (2), 1 to 45% by mole of the unit (3) derived from a monomer having a chemically curable functional group, 1 to 45% by mole of the unit (4) derived from a monomer having ester moieties in the side chains and 0 to 45% by mole of the unit (5) derived from a copolymerizable monomer other than the above monomers, if necessary, 0.1 to 15% by mole of the unit (6) derived from a monomer having carboxyl groups. The copolymer can provide a curable composition alone or with an acrylic polymer. The fluorine-containing copolymer is excellent in solvent-solubility, compatibility with curing agents, additives and other polymers, pigment dispersibility, curing reactivity, dispersibility to water, pot life, film forming ability, coating properties, and the like. The coating film prepared from the copolymer has a high weatherability and is excellent in film properties such as stain resistance, heat-yellowing resistance, dechlorination resistance, optical properties, adhesion to a substrate, mechanical properties, heat resistance, chemical resistance, solvent (gasoline) resistance, water resistance and good appearance of finished products.