A polyester film which contains 0.01 to 5.0 wt.% of a lubricant having an average particle diameter of 0.001 to 2.5 mu m and is suitable for use in sticking to the surface of an easy-to-open can lid in contact with the contents, and which has been regulated so as to have a coefficient of plane orientation of 0.115 to 0.140, at least two endothermic peaks in the range of 170 to 270 DEG C in DSC, a peak temperature of complex elastic modulus (E") in water of 60 to 120 DEG C, and an intrinsic viscosity of 0.50 to 0.64 dl/g. Because of these properties, the film has excellent processability in lid formation after being stuck to a metal sheet and has excellent corrosion resistance even when held at high temperatures.