Packaging device allowing two or more products that are mixed at the time of use thereof to be expended in a single package, including a package differentiated in two or more enclosures, one of them provided with an openable stopper, separated by a movable stoppering partition and each filled with one of the products to be contained separately in the package and with a gaseous fluid compatible with each of said products, the gaseous fluid being substantially subject to pressures different from normal atmospheric pressure, which pressures exert an equal force on opposite faces of the internal movable stoppering partition, maintaining a balance between both enclosures.