An airbag is manufactured by sewing a base fabric woven with a first polar fiber by means of a sewing thread. The sewing thread is made up of a yarn formed from a second polar fiber such as nylon 66, and the yarn is subjected to a lubrication treatment using a lubricating agent that consists of a polar group-containing compound having an action to improve lubricity of the sewing thread or that contains mainly such a polar group-containing compound.