a packing member for packing an article , includes a medium accommodating portion for accommodating medium ; a non - return valve for passing the medium to the medium accommodating portion and stopping the medium away from the medium accommodating portion ; an introducing portion for introducing the medium into the medium accommodating portion with the non - return valve from an outside of the packing member to balloon the medium accommodating portion ; and a sealing region , disposed upstream of the non - return valve with respect to a direction of the introduction of the medium from the introducing portion toward the non - return valve , for sealing against the introduction of the medium to prevent leakage from the introducing portion to an outside of the packing member , the sealing region being sealed to keep the medium in the medium accommodating portion .