Method for manufacturing airbag

A method of manufacturing an airbag, wherein

• the airbag is formed into a bag shape by joining peripheral portions of two main body fabric portions and has an inflation portion that is inflated by inflation gas,
• the airbag includes two structural fabric portions,
• a first partition is installed to extend between the main body fabric portions,
• a second partition having an extended end is installed to extend between the main body fabric portions in a state in which the second partition extends in a direction intersecting with the first partition and the extended end is overlaid onto the structural fabric portions,
• at least a part of the inflation portion is divided into a plurality of inflation chambers by the first partition and the second partition,
• the second partition includes two fabric pieces, which are independent from each other and at least one of the fabric pieces has an inner discharge hole,
• a first joining step, in which a peripheral portion in each structural fabric portion that is brought closer to the main body fabric portions at the installation is joined to the main body fabric portions in a spread state;
• a second joining step, in which, in an outer peripheral portion of each fabric piece of the second partition, a part that is not overlaid onto the structural fabric portions is joined to the main body fabric portions, and a part that is overlaid onto the structural fabric portions is joined only to the structural portions;
• a coupling step for coupling the fabric pieces to each other at inner peripheral portions thereof;
• and
• a third joining step, in which peripheral portions of the structural fabric portions that are separated away from the main body fabric portions at the installation are joined to each other.