By forming a polyester film from a polyester resin composition including ketene imine compound represented by the following Formula (1) and polyester, the polyester film having excellent hydrolysis resistance in which volatilization of the ketene imine compound or the ketene compound can be suppressed. In Formula (1), R1 and R2 represent an alkyl group, an aryl group, an alkoxy group, an alkoxycarbonyl group, an aminocarbonyl group, an aryloxy group, an acyl group, or an aryloxycarbonyl group, and the R1—C(═C)—R2 substructure has a molecular weight of 320 or greater. R3 represents an alkyl group or an aryl group.