The present invention provides a polyester resin which is excellent in long-term thermal stability and moldability, comprises a dicarboxylic acid component and a glycol component, wherein 10 mol% or more of a furandicarboxylic acid is contained as the dicarboxylic acid component and the polyester resin satisfies following requirements (1) to (3);
(1) a total metal element content is 150 ppm or less relative to the mass of the polyester resin;
(2) a phosphorus element content is 100 ppm or less relative to the mass of the polyester resin; and
(3) TODΔ reduced viscosity represented by the following formula is 0.030 dl/g or less;
TODΔ reduced viscosity = reduced viscosity before thermal oxidation test − reduced viscosity after thermal oxidation test .