Provided are: a polyester resin (C) which has a sufficiently high molecular weight, which has a high degree of crystallinity, and which has an amide group in the molecular chain; and a manufacturing method of the polyester resin (C). Further provided are a polyester resin (C) which has a sufficiently high molecular weight, which has a high degree of crystallinity, which is biodegradable, and which has an amide group in the molecular chain; and a manufacturing method of the polyester resin (C). The polyester resin (C) is obtained by reacting an aliphatic polyester resin (A) and a polyisocyanate compound (B) in the presence of an amidation catalyst, and is characterized by containing a specific constituent unit.