PURPOSE: To eliminate the transverse wrinkles of a film without damaging it, by providing rollers having rotary shafts oblique to the proceeding direction of the film.

CONSTITUTION: A film 3 is pulled and conveyed in a direction shown by an arrow in the drawing, as the film is wound by angles on rollers 4, 5. Other rollers 6, 7, provided so that their axes are oblique at an angle of θ to the proceeding direction of the film, the peripheral surfaces of the rollers are in contact with the side edges (a), (b) of the film and the rollers are rotated together with the proceeding of the film. As the rollers 6, 7 are rotated, a frictional force is caused on the contact line of the film and each of the rollers 6, 7 so that the force's component perpendicular to the proceeding direction of the film acts to increase its width to eliminate its wrinkles. The angle of θ is appropriately determined depending on the width, thickness, tension and conveyance speed of the film 3, coefficient of friction between the film and the rollers, widths (a), (b) of discarded portions of the film, etc.