In an aspect of the present invention, since the maximum linear pressure when a sheet-like melted resin is nipped between an elastic roller and a cooling roller is controlled at 0.3 MPa to 3 MPa, the development of retardation in film forming can be prevented. According to the aspect, since an elastic roller and a cooling roller are rotated at nearly the same speed with the periphery speed ratio thereof at 0.99 to 1.01, a sheet-like melted resin can be transported without applying a stress caused by a rotation difference between the rollers, whereby the development of retardation on the unstretched thermoplastic resin film can be prevented. Further, since the surface temperature of a cooling roller is controlled so as to be 0.01° C. to 30° C. higher than that of an elastic roller, a sheet-like melted resin is pulled toward the elastic roller side, whereby the development of retardation can be prevented.