To provide a thermoplastic resin film suppressing the development of retardation by suppressing the occurrence of strain due to a polishing roller method and obtaining a film having high optical characteristics, and its manufacturing method.

A molten resin is extruded in a sheet-like form from a die 24 to be supplied to the nip between a pair of polishing rollers 26 and 28 and cooled while pressed by a pair of the polishing rollers 26 and 28 to form a cellulose acylate film. At least one polishing roller 26 is constituted of an elastic roll made of a metal.