PURPOSE: To completely remove wrinkles of a film by disposing means for smoothing out a film at a fixed space from a straight roll 8 for conveying a film and forming high-pressure air jet slits on a portion of the means that is confronted with the straight roll.

CONSTITUTION: Smooth-out means 10 for a film 7 is disposed at a fixed space from a straight roll 8 and high-pressure air is supplied to a chamber 12 of the means 10. A plurality of air jet slits 13 are formed on the top plate portion of the above means 10, and a straight air jet slit 14 is also formed on the end portion thereof. High-pressure air is continuously jetted out from the slits 13 to smooth out a film 7 from the central part to the end surfaces. The film 7 is closely adhered to the straight roll 8 by high-pressure air jetted out from the slit 4 to prevent the film 7 from being wrinkled again. Thus, the film 7 can be kept good in quality.