A composite film is disclosed which includes (a) a synthetic resin substrate film having a roughened surface, and (b) a thin, slippery, electrically conducting layer coated over the roughened surface. The conducting layer contains 2-10% by weight of carbon black, 10-40% by weight of a fluorine resin, 25-78% by weight of a hardened binder resin selected from hardened amino resins, hardened phenol resins and mixtures thereof, and 7-25% by weight of a modifying resin selected from polyurethane resins, acrylic resins, polyester resins and mixtures thereof, the total amount of the hardened binder resin and the modifying resin being 50-85% by weight.