Provide are a novel polyester resin that can be used for producing a molded article excellent in impact resistance, and a method of producing the polyester resin. The polyester resin has structural units represented by the following general formulae (1) and (2), and contains the structural unit represented by the general formula (2) at a content of 50.1 mol % or more to 99.9 mol % or less with respect to the total of the structural units represented by the general formulae (1) and (2). The method of producing a polyester resin, includes copolymerizing a furandicarboxylic acid or an ester thereof with ethylene glycol and diethylene glycol. In the formula, R1 represents an aromatic hydrocarbon group which may be substituted, or an aliphatic hydrocarbon group which may be substituted.