To obtain the subject composition, consisting essentially of a specific fluorine-containing copolymer, excellent in flexibility, weatherability, fouling and water resistances and adhesion to a metal, curable at normal temperature and useful in the field of sealing compounds.

This highly weather resistant sealing compound composition consists essentially of a fluorine-containing copolymer comprising (A) a fluoroolefin, (B) a compound of the formula CH2=CHR (R is a 1-20C alkyl, a cycloalkyl, an aryl or a halogen-containing alkyl), (C) a compound of the formula R-SiXnY3-n [R is a group having an olefinic unsaturated bond; X is a 1-20C alkyl; Y is an alkoxy; (n) is 0-2] and (D) other copolymerizable monomers and has ≤0°C glass transition temperature. The amounts of the components based on the total amount of the whole constituent monomers are 20-70mol% component A, 20-70mol% component B, 1-20mol% component C and 0-60mol% component D.