To provide a method for manufacturing a norbornene resin film having no appearance defectiveness such as the deteriorated resin caused by thermal deterioration, a die line, air bubbles or the like, not lowered in strength and not generating these problems even if a polymer film is used.

In the method for manufacturing the norbornene resin film by melt extrusion molding, a ratio Mw2/Mw1 of the weight average mol.wt. (Mw1) before extrusion molding and the weight average mol.wt. (Mw2) after extrusion molding is 0.87-1.03.