The present invention relates to a method for manufacturing a polymer film, the method comprising a base film forming step for co-extruding a first resin containing a polyamide-based resin and a second resin containing a copolymer including a polyamaide-based segment and a polyether based segment; to a co-extruded film comprising a base film including a first resin layer containing a polyamaide-based resin; and a second resin layer containing a copolymer having a polyamaide-based segment and a polyether-based segment; to a co-extruded film comprising a base film including a first resin layer and a second resin layer, which have different melting points; and to a method for manufacturing a polymer film, the method comprising a base film forming step of including a step of co-extruding a first resin and a second resin, which have different melting points.