SOLUTION CASTING METHOD

A dope is cast onto a drum whose surface is cooled, so as to form a casting film. After the peeling of the casting film, a cleaning gas containing dry ice particles is applied to a periphery of the casting drum with use of a drum cleaning unit. Thus the dry ice particles collide to the periphery of the casting drum, and the colliding energy is effective of removing from the periphery an organic material adhered on the casting drum. The organic material mainly contains aliphatic acid, aliphatic acid ester and metal salt of aliphatic acid. Before the increase of the amount of the organic material, it is removed and therefore isn't transmitted onto the surface of the casting film. Thus a high quality film having no optical unevenness is produced without the decrease of the productivity.