An air-packing device has an improved shock absorbing capability to protect a product in a container box. The air-packing device is comprised of first and second thermoplastic films where predetermined portions are bonded thereby creating a plurality of air containers, a plurality of heat-seal lands each sealing the first and second thermoplastic films in a small area of the air container thereby creating a plurality of series connected air cells for each air container, a plurality of check valves for corresponding air containers for allowing the compressed air to flow in a forward direction, and at least one pocket formed of a sheet of thermoplastic film bonded to either the first thermoplastic film or the second thermoplatic film at boundaries between two adjacent air containers. The air-packing device is folded after the product is inserted in the pocket and installed in a container box.