To reduce the occurrence of longitudinal wrinkles by conveying a band-shaped resin film with relatively low conveying tension and scratches cased by a roll slip by relatively increasing friction force between the resin film and a roll when an optical film is manufactured by solution flow casting or melting casting.
A manufacturing method of the optical film has steps of winding the band-shaped resin film 53 around a plurality of rotatable rolls 21, and conveying the resin film 53 in a longitudinal direction by applying a conveying tension to the resin film 53 in the longitudinal direction. The conveying tension applied to the resin film 53 in the longitudinal direction is set to 30 to 180 N/m, and a wind 22a, the velocity of which is 0.2 m/s or more, is blown to the entire width of the resin film 53 that contacts the circumferential surface of the roll 21 from the reverse side of the roll.
Masataka Otani
Toda Shunza