Method for manufacturing a wide film, and wide film

A method for manufacturing a wide film, comprising:

• a casting operation which is a process of casting a film using a wide casting belt including a central belt, a left belt having a right end formed integrally with a left end of the central belt through a left joint in a length direction of the central belt, and a right belt having a left end formed integrally with a right end of the central belt through a right joint in the length direction of the central belt;
• a stretching operation which is a process of gripping and stretching predetermined regions of left and right sides of the cast film stripped off from the wide casting belt using a tenter so that the cast film is extended in a width direction thereof;
• a first trimming operation which is a process of removing predetermined parts of left and right sides of the film excluding regions at which marks are formed by the left joint and the right joint of the wide casting belt after the stretching operation;
• a drying operation which is a process of drying the trimmed film after the first trimming operation;
• and
• a second trimming operation which is a process of removing parts of left and right sides of the dried film including regions at which mark are formed by the left joint and right joint of the wide casing belt after the drying operation.