A gas barrier laminate having an undercoating (A) which comprises a main resin, an isocyanate type curing agent and an alkaline compound of a polyvalent metal; and a barrier layer (B) of a polycarboxylic acid polymer forming an ionic crosslinking due to the polyvalent metal among the carboxyl groups; formed on at least one surface of a plastic base material (P), wherein a region (b) free of the alkaline compound of the polyvalent metal is formed in the undercoating (A) on the side of the barrier layer (B), the content of nitrogen in the region (b) being larger than the content of nitrogen in the undercoating (A) other than the region (b), the gas barrier laminate having excellent gas barrier property, retort resistance, producibility as well as excellent flexibility without developing interlayer peeling even if it is folded and featuring excellent interlayer adhesion.