To impart not only excellent transparency, gas barrier properties or the like but also excellent post-processing aptitude such as printing, lamination, bag making or the like by providing a coating film based on a silicon oxide film heat-treated under a constant temp. and constant humidity temp. by a polysilazane-containing coating soln. on the surface of a vapor deposition film of inorg. oxide.

A vapor deposition film 3 of inorg. oxide is provided on the surface of a base material film 2 and a coating film 4 based on a silicon oxide film is provided on the surface of this vapor deposition film 3. That is, aluminum is used as a vapor deposition source and a vapor deposition film of aluminum with a thickness of 200 is formed on the single surface of a biaxially stretched polyethylene terephthalate film with a thickness of 12 μm by a vacuum vapor deposition method by an electron beam heating system while supplying oxygen gas. Further, a soln. containing 20 wt.% polysilazane is applied to the surface of the vapor deposition film by a bar coater and the coated film is heated at 120°C for 1 hr by a dryer to form a coating film based on silicon oxide with a thickness of 1.2 μm.