For continuous production of a resin film having a plain surface, a resin solution cast in film form over an endless belt is pre-hardened by a gas stream supplied for flow in a direction generally parallel to the surface of the endless belt, and then a jet of gas is blown in the direction of movement of the endless belt whereby the resin is hardened. In the process for resin film production wherein the resin film is cast over the endless belt and then pre-hardened by a parallel gas stream, the cast film being then hardened by a jet of gas, the installation for production is divided by partitions so as to enable various stages to be operated independently.