Abstract: A substantially random, linear vinylidene fluoride-acrylic acid ester copolymer comprising:(A) 5-85% by weight of a vinylidene fluoride unit,(B) 15-95% by weight of at least one unit selected from the group consisting of an alkyl acrylate unit and an alkoxy-substituted alkyl acrylate unit, and(C) optionally 10% by weight or less, based on the total weight of (A), (B) and (C), of a crosslinking monomer unit, and having an intrinsic viscosity of 0.01-10 dl/g as measured at 30.degree. C. in N,N-dimethylformamide. Said copolymer has not only excellent heat resistance, ozone resistance and sour gasoline resistance but also excellent resistance to gasoline permeation.