PURPOSE: To get rid of generation of curl, and also to elevate running stability, by providing a back coating layer containing fluorine oil in specific resin, on the reverse side of a base body on which a ferromagnetic metallic thin film layer has been formed by means of vapor deposition.

CONSTITUTION: On the reverse side of the base of a polyester film, etc. having on the surface a ferromagnetic metallic thin film layer formed by means of vapor-deposition of cobalt, etc., a layer consisting of at least one resin selected from an acrylonitrile-butadiene-styrene copolymer, polystyrene resin, acrylic resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetal resin, and cellulose resin, and fluorine oil of perfluoroalkyl polyether, polytrichloro-trifluoroethane, etc. is provided.