PURPOSE: To prevent the generation of rust when an object to be packed is a metal member and to prevent deterioration when the object to be packed is food, by wrapping the object to be packed in a single or composite packing sheet having at least heat-sealability and a gas barrier property in a bag form and removing the oxygen gas in the bag body to enclose nitrogen gas in said bag body.

CONSTITUTION: The first packing sheet 2 is laid on a substrate 1 and an object 3 to be packed is placed thereon. The object 3 to be packed is covered with the second packing sheet 4 in a bag form, and the edge part of the second packing sheet 4 and that of the first packing sheet 2 are thermally welded, bonded and hermetically sealed to form a bag body. A vacuum pump 7 is operated to discharge the air in the bag body. At this time, the bag body consisting of the first and second packing sheets 2, 4 are heated and softened. A three-way cock 6 is opened on the side of a nitrogen gas cylinder 8 to enclose nitrogen gas in the bag body until the internal pressure of the bag body becomes about 1 atm. Continuously, the packing sheets 2, 4 around a discharge pipe 5 are thermally welded each other and the discharge pipe 5 is cut off from the bag body. The first and second packing sheets 2, 4 used at this time are composed of a single or composite sheet having both of heat-sealability and a gas barrier property.