Abstract: A pressure-packing container comprises an impervious container body having an internally recessed upper edge, and an easy-to-open closure cap composed of a rigid outer closure member having an annular rim, a resilient inner closure member joined with the underside of the outer closure member, and a sheet of impervious film bonded with the inner closure member. To close the container, an inner peripheral wall of the rim is plastically deformed to force a portion of the inner closure member to flex into a groove in the upper edge, with an outer edge of the impervious film sheet sandwiched between the deformed inner closure member and the grooved upper edge, thereby providing a hermetic seal strong enough to withstand the inside pressure of the container.