To provide a method of manufacturing a film using a cooling device, which has high productivity and is capable of producing a thick film being excellent in haze at a high speed without generating film thickness unevenness due to the unevenness formed on the film surface in the cooling device for cooling the thermoplastic resin film on an anti-cooling drum surface.

The cooling device, for cooling the anti-cooling drum surface film on the cooling drum by blowing air to the film from a blowing nozzle, has a means for measuring the film surface temperature on an anti-drum surface and optionally adjusting the wind velocity of air blown toward the film from a plurality of nozzle mounted on the anti-cooling drum surface. The film manufacturing method uses the cooling device for adjusting the wind velocity in accordance with the degree of the film thickness unevenness while measuring the film thickness unevenness in the film flow direction by a film thickness meter mounted in an cooling drum outlet.