A check valve for use in an air-packing device has a simple structure and promotes to easily inflate all of the air cells of the air-packing device with a relatively lower pressure. The check valves can be easily attached to any locations of the air-packing device. The check valves are formed when a check valve film is attached to one of the first and second thermoplastic films. Peeling agents of predetermined pattern are applied on the check valve film which prevents heat-sealing between the first and second thermoplastic films for air tightly separating two adjacent air containers. The check valve is configured by an air flow maze portion having a zig-zag air passage and a common air duct portion which provides the air to the air flow maze portion of a current air container as well as to the air flow maze portion of a next air container.