A gas-barrier material comprising a polycarboxylic acid polymer (A) and a compound (B) having two ring structures (b) each of which forming an ether bond to carbon that forms a double bond with nitrogen and containing oxygen in the ether bond, wherein a crosslinked structure is formed by the reaction of a carboxyl group in the polycarboxylic acid polymer (A) with one of the ring structures (b) of the compound (B). The gas-barrier material features excellent gas-barrier property, retort resistance and flexibility, can be cured at a low temperature within short periods of time, and can be excellently produced.