Abstract: A polyester composition is disclosed which includes a polyester, (a) a thermoplastic elastomer and (b) a carbodiimide compound having at least one carbodiimide group and which exhibits improved impact resistance at low temperatures and stability to heat, hot water and steam. The composition is useful to form parts which are exposed to low temperatures. A polyalkylene terephthalate resin composition is also disclosed which includes a polyalkylene terephthalate resin, (a) at least one selected from the group consisting of ethylene/alkyl acrylate and a thermoplastic polyester elastomer and (b) at least one selected from the group consisting of an epoxy resin containing at least two carbodiimide groups in the molecule.