A polyester composition includes a ligand capable of coordinating to a metal or metal ion, wherein the ligand includes at least one donor atom selected from the group consisting of a nitrogen atom, a sulfur atom, and an oxygen atom. Consequently, it is possible to inactivate a metal catalyst which adversely affects heat resistance. As a result, it is possible to obtain polyester compositions and films having excellent heat resistance, colorability, and weathering resistance. Moreover, in the process of producing a polyester, by separating and recovering a catalyst by adding a ligand which is capable of coordinating to a metal or metal ion and which includes at least one donor atom selected from the group consisting of a nitrogen atom, a sulfur atom, and an oxygen atom, it is possible to improve the heat resistance of the polyester composition.