Vinylidene chloride copolymer resin compositions excellent in thermal stability during extrusion molding and reduced in discoloration caused by thermal deterioration. One of the compositions comprises a vinylidene chloride resin, an ethylenediaminetetraacetic acid salt, and a salt of an organic weak acid. The process for producing the vinylidene chloride resin composition comprises polymerizing vinylidene chloride monomer with at least one ethylenediaminetetraacetic acid salt in the presence of at least one organic weak acid salt at a pH of the polymerization system of 3 or higher and regulating the pH of the aqueous phase at completion of the polymerization to 3 to 6. Another of the compositions comprises a vinylidene chloride copolymer and a salt of a weak acid, the copolymer having a reduced viscosity of 0.040 to 0.057 l/g and the salt being one selected from the group consisting of salts of organic weak acids containing no nitrogen atom and inorganic phosphoric acid salts, and is excellent in productivity in extrusion. The film is obtained by extruding this vinylidene chloride resin composition by using a vacuum hopper.