A polyester film according to one embodiment has improved thermal properties and chemical properties by controlling the crystallinity of a copolymerized polyester and, particularly, exhibits excellent shrinkage per unit temperature as well as adhesiveness by means of a solvent, and thus is suitable for a heat-shrinking process and a seaming process. Therefore, the polyester film according to said embodiment can be usefully applied, as a heat-shrinkable label or packaging material, to containers of various products comprising drinks or food.