Abstract: [Problems] To provide a norbornene compound addition polymer film that is excellent in heat resistance, chemical resistance, dimensional stability and the like and favorable for use for optical parts and electric insulating parts. [Means for Solving Problems] The norbornene compound addition polymer film satisfies at least either one of the following: when it is heated from 25° C. up to 200° C. and then again cooled to 25° C., the dimensional change rate thereof between before heating and after cooling is at most 100 ppm, or the dimensional change rate thereof between before and after dipping in propylene glycol monomethyl ether acetate at 25° C. for 1 hour is at most 100 ppm. The method for producing the norbornene compound addition polymer film comprises a step of maintaining the film having a residual solvent content of at most 5,000 ppm of the norbornene compound addition polymer having a glass transition temperature of T° C.

Abstract: [PROBLEMS] To provide: a norbornene compound addition polymer which has excellent heat resistance and suffers no decrease in the excellent transparency and mechanical properties even when exposed to high temperatures during molding, processing, or use; and a process for producing the polymer. [MEANS FOR SOLVING PROBLEMS] The norbornene compound addition polymer comprises, as an essential ingredient, repeating structural units derived from a substituted norbornene compound monomer, wherein the total content of atoms of the transition metals in Group 10 of the Periodic Table, halogen atoms, phosphorus atoms, aluminum atoms, boron atoms, and sulfur atoms is 50 wt. ppm or lower. The process for producing a norbornene compound addition polymer comprises bringing a norbornene compound addition polymer comprising, as an essential ingredient, repeating structural units derived from a substituted norbornene compound monomer into contact with an ion-exchanging lamellar inorganic compound.