A method for charging a bag equipped with gas compartment with a gas, wherein said method uses a bag equipped with gas compartment, the bag being formed integrally therewith a gas compartment portion extending in a longitudinal direction in a sealed side edge portion of the bag and formed with a gas inlet which is for placing exterior of the bag in communication with interior of the gas compartment portion and is provided in a surface of a film that makes the gas compartment portion, and said method charges the gas compartment portion with a gas by: aligning a discharge outlet of a nozzle connected to a pressurized gas supply source with the gas inlet, injecting gas from the nozzle into the gas compartment portion through the gas inlet, while the injection is in progress, gripping a blockage region configured in a vicinity of the gas inlet with a gas blocking gripper on both sides of the bag to thereby block fluid communication of the gas between the gas inlet and the interior of the gas compartment portion, and then, while maintaining the blocked state, gripping both sides of the bag in a location of the gas inlet or in a location in the vicinity of the gas inlet with hot plates to seal the gas inlet or the location in the vicinity of the gas inlet, characterized in that during the injection of the gas into the gas compartment portion to expand the gas compartment portion, said method restricts, from both sides of the bag, expansion of restriction region configured in a vicinity of the blockage region, so that an expanded shape of the restriction region is restricted to a flat configuration. wherein said method uses a bag equipped with gas compartment, the bag being formed integrally therewith a gas compartment portion extending in a longitudinal direction in a sealed side edge portion of the bag and formed with a gas inlet which is for placing exterior of the bag in communication with interior of the gas compartment portion and is provided in a surface of a film that makes the gas compartment portion, and said method charges the gas compartment portion with a gas by: aligning a discharge outlet of a nozzle connected to a pressurized gas supply source with the gas inlet, injecting gas from the nozzle into the gas compartment portion through the gas inlet, while the injection is in progress, gripping a blockage region configured in a vicinity of the gas inlet with a gas blocking gripper on both sides of the bag to thereby block fluid communication of the gas between the gas inlet and the interior of the gas compartment portion, and then, while maintaining the blocked state, gripping both sides of the bag in a location of the gas inlet or in a location in the vicinity of the gas inlet with hot plates to seal the gas inlet or the location in the vicinity of the gas inlet, characterized in that during the injection of the gas into the gas compartment portion to expand the gas compartment portion, said method restricts, from both sides of the bag, expansion of restriction region configured in a vicinity of the blockage region, so that an expanded shape of the restriction region is restricted to a flat configuration. aligning a discharge outlet of a nozzle connected to a pressurized gas supply source with the gas inlet, injecting gas from the nozzle into the gas compartment portion through the gas inlet, while the injection is in progress, gripping a blockage region configured in a vicinity of the gas inlet with a gas blocking gripper on both sides of the bag to thereby block fluid communication of the gas between the gas inlet and the interior of the gas compartment portion, and then, while maintaining the blocked state, gripping both sides of the bag in a location of the gas inlet or in a location in the vicinity of the gas inlet with hot plates to seal the gas inlet or the location in the vicinity of the gas inlet, characterized in that during the injection of the gas into the gas compartment portion to expand the gas compartment portion, said method restricts, from both sides of the bag, expansion of restriction region configured in a vicinity of the blockage region, so that an expanded shape of the restriction region is restricted to a flat configuration.