PURPOSE: To prevent the formation of wrinkles of a film on the surface layer part of a taking-up core by taking-up the film, keeping the deflection of the taking-up core at the start of taking-up less than a specific factor of the thickness of the film.

CONSTITUTION: When polyester film is taken-up onto a taking-up core 2 whose borh edges are supported in contact with a joint roller 4, the film is taken-up, keeping the deflection of the taking-up core 2 at the start of taking-up less than 15 times of the thickness of the film. Therefore, the generation of wrinkles of the film on the surface layer part of the taking-up core 2 can be prevented. In this case, a taking-up core 2 having a small deflection and a large bending modulus can be sufficiently used, for example, a core having a bending modulus of 2,000kg/mm2 or more obtained through filament winding shaping can be used.