METHOD FOR MANUFACTURING RETARDATION FILM

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polypropylene-based resin retardation film having high axis accuracy and uniform phase difference value.SOLUTION: The method for manufacturing the polypropylene-based resin retardation film includes: (A) longitudinally stretching a rolled film made of a polypropylene-based resin; (B) curing the longitudinally stretched rolled film under the environment of a temperature of T°C between 0-40°C; and (C) laterally stretching the cured rolled film, in this order. The curing step (B) is conducted so as to satisfy the expression: D≥-0.4T+20 on the basis of a curing period as D day. Typically, the method includes: (A) longitudinally stretching the rolled film made of the polypropylene-based resin; (B) curing the longitudinally stretched rolled film under the environment of a temperature of between 20-30°C for 10 days or more; and (C) laterally stretching the cured rolled film, in this order.