The present invention provides a polyvinylidene fluoride copolymer capable of forming a uniform film, a solution of the copolymer and a thin film comprising the polyvinylidene fluoride copolymer. The polyvinylidene fluoride copolymer of the present invention is characterized in that the ratio of the scattered-light intensity (I) for a 15% solution of the polyvinylidene fluoride copolymer in dimethylformamide solvent to the scattered-light intensity (I.sub.0) for dimethylformamide, (I/I.sub.0), is 10 or lower. The polyvinylidene fluoride copolymer solution comprises the polyvinylidene fluoride copolymer and an organic solvent capable of dissolving the copolymer.