An aromatic polyester resin composition, including: a melt-kneaded product of 99-70 wt. parts of an aromatic polyester resin and 1-30 wt. parts (providing a total of 100 wt. parts together with the aromatic polyester resin) of a polyglycolic acid resin, wherein the aromatic polyester resin is an aromatic polyester resin polymerized with a germanium compound (catalyst), and the polyglycolic acid resin is a polyglycolic acid resin obtained by ring-opening polymerization of glycolide. As a result, gas generation during the melt-processing of a composition obtained by adding a relatively small amount of polyglycolic acid resin to an aromatic polyester resin is effectively suppressed to provide an aromatic polyester resin composition with a good gas-barrier property.