A gas-barrier material in which carboxyl groups are ionically crosslinked in an amount corresponding to an acid value of at least 330 mgKOH/g of a resin that has the carboxyl groups in an amount corresponding to an acid value of not smaller than 580 mgKOH/g. The gas-barrier material exhibits excellent gas-barrier property, retort resistance and flexibility under highly humid conditions, enables the film to be cured at a low temperature in a short period of time, and can be favorably produced.