Abstract: The inventive airtight closure device (2) for a container (1) containing a product to be packed is characterised in that it comprises a base (3) whose circumference is adjustable to the internal wall of the container (1) in such a way that it is possible to bring the internal face (4) of the base (3) into contact with the product by displacing the base (3) which provided with at least one air discharging hole closable after the base (3) is mounted. A container provided with the inventive device is also disclosed. Said invention is particularly suitable for packing food products, in particular in a liquid, pasty and powder form.