NOVELTY - A polyester film is obtained by supplying a raw material containing polyester resin and carbodiimide type terminal blocker to a twin-screw extruder (100), melt-kneading, extruding, and molding. The resin fullness from exit (14) of extruder cylinder (10) is set in a region more than or equal to 3 times the diameter of screw (20A,20B) and less than or equal to 7 times screw diameter. The molten resin is extruded while controlling the cylinder temperature in resin-fullness region at (melting point of polyester resin-150) degrees C to resin melting point.    USE - Manufacture of polyester film for protection sheets of solar cells used in solar-cell modules (all claimed) of single crystal silicon, polycrystalline silicon, or amorphous silicon type.    ADVANTAGE - The method enables manufacture of polyester films having excellent hydrolysis resistance and weather resistance, using less amount of terminal blocker. Thus, volatilization of terminal blocker is restrained and working environment is improved.    DETAILED DESCRIPTION - A polyester film is obtained by supplying a raw material containing a polyester resin having an intrinsic viscosity of 0.7-0.85 dl/g and a carbodiimide type terminal blocker having a sealing reactive functional group number of 3-60 eq/ton, to a twin-screw extruder, melt-kneading, extruding, and molding the extruded molten resin. The resin fullness from the exit of cylinder of the extruder is set in a region more than or equal to 3 times screw diameter and less than or equal to 7 times screw diameter. The molten resin is extruded while controlling the cylinder temperature in the resin-fullness region at (melting point of polyester resin-150) degrees C to melting point of polyester resin. An INDEPENDENT CLAIM is included for polyester film containing 1-40 eq/ton unreacted carbodiimide type terminal blocker.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the twin-screw extruder used for manufacturing polyester film.    Cylinder (10)    Exit (14)    Vent ports (16A,16B)    Screws (20A,20B)    Twin-screw extruder (100)