To provide a novel polyester resin that exhibits excellent molding processability and gives a molded article excellent in impact resistance.

The polyester resin primarily comprises a dicarboxylic acid unit comprising a terephthalic acid unit (I) and a 1,4-cyclohexane dicarboxylic acid unit (II) and/or an isophthalic acid unit (III) and a diol unit comprising an ethylene glycol unit (IV) and a 1,4-cyclohexane dimethanol unit (V) and has a melting point of 210-250°C and an intrinsic viscosity of 0.6-1.5 dl/g wherein a molar ratio of the constitutional units is given alternatively as A : I: (II +III)=97:3-90:10 and IV:V=97:3-88:12 or as B : I: (II+III)=95:5-80:20 and IV:V=20:80-5:95.