PURPOSE: To obtain a thin film of high quality having a flexible film as a substrate at a low cost, by adhering a flexible film closely to a beltlike member, winding up the resultant laminated member, forming a thin film on the surface of the flexible film under reduced pressure while transferring them.

CONSTITUTION: A flexible film 1 is closely adhered to a beltlike member 2 consisting of a metal or plastic, etc., and the resultant laminated member 3 is then wound into a roll 4. The laminated member 3 is then withdrawn and introduced into a vessel 7 having a means for forming a thin film, e.g. the sputtering or vapor depositing method, etc., and a material, e.g. Co, Fe or Si, capable of exhibiting the function is deposited on one side of the flexible film 1 while sliding the laminated member 3 on a hot plate 9 at a controlled temperature under reduced pressure to form the aimed thin film.

EFFECT: The temperature control of the film can be carried out with certainty without applying an excess tension to the flexible film 1.