A gas-barrier multilayered structure comprising (A) at least one layer of a copolyamide composed of (a) a dicarboxylic acid component composed of 55 to 70 mole % of an aliphatic dicarboxylic acid component and 45 to 30 mole % of an aromatic dicarboxylic acid component consisting substantially of 20 to 30 mole % of isophthalic acid and 5 to 20 mole % of terephthalic acid, and (b) a diamine component composed substantially of a m-xylylenediamine component, and (B) at least one layer of a thermoplastic resin other than the copolyamide. Instead of the layer (A), there can be used (A') at least one layer of a mixture of 40 to 60 % by weight of a first copolyamide composed of (a) a dicarboxylic acid component composed of 55 to 70 mole % of an aliphatic dicarboxylic acid component and 45 to 30 mole % of an aromatic dicarboxylic acid component consisting substantially of 20 to 30 mole % of isophthalic acid and 5 to 20 mole % of terephthalic acid and (b) a diamine component composed substantially of m-xylylenediamine and 60 to 40 % by weight of a second polyamide composed of a dicarboxylic acid component consisting substantially of an aliphthalic dicarboxylic acid component and a diamine component consisting substantially of a m-xylylenediamine component.