A saturated polyester resin composition excellent in impact resistance is prepared by melt kneading (A) 30-58 parts by weight of a saturated polyester resin, (B) 42-70 parts by weight of an epoxy group-containing ethylene copolymer comprising (a) 50-99% by weight of ethylene unit, (b) 0.1-30% by weight of unsaturated carboxylic acid glycidyl ester unit or unsaturated glycidyl ether unit, and (c) 0-49% by weight of ethylenically unsaturated ester compound unit, (C) 0.01-20 parts by weight of a polyfunctional compound containing at least two specific functional groups of amino groups, carboxyl groups, carboxylic acid anhydride groups, hydroxyl groups or

unit (wherein X and Y are both oxygen atoms or sulfur atoms or one of them is an oxygen atom and another is a sulfur atom) and (D) 0-30 parts by weight of a block copolyether ester elastomer, the amounts of (C) and (D) being based on 100 parts by weight of (A) plus (B), thereby to obtain a former-stage composition (I) and furthermore melt kneading the resulting composition (I) with (E) 50-1000 parts by weight of a saturated polyester resin and (F) 0-30 parts by weight of a block copolyether ester elastomer at a later-stage.