Disclosed herein is a polyester composition which comprises a polyester with a terminal carboxyl group content of 40 to 80 equivalents/10.sup.6 and 0.0 to 5 wt %, based on the total amount of the polyester composition, aluminum oxide particles of 0.005 to 5 .mu.m in average particle diameter and which has a melt resistivity of 6 x 10.sup.6 to 5 x 10.sup.8 .OMEGA..cm.By using the polyester composition, it is possible to successively produce a film having excellent wear resistance and flatness over a long production run.