A gas-barrier laminate comprising a base film, a thin film formed on the base film and comprising a metal compound selected from the group consisting of oxides, carbides and nitrides of metals, and mixtures thereof, and a plastic film formed on the metal compound thin film in which a film obtained by forming the metal compound thin film on the base film is subjected to a heat treatment, and having an oxygen permeability of not more than 2 cc/m.sup.2/day/atm, wherein when the laminate is subjected to hydrothermal treatment at 120.degree. C. for 30 min, a change in oxygen permeability of the laminate between before and after the hydrothermal treatment is not more than 5.