AIRBAG

An airbag includes panels, which face each other, of an outer peripheral wall upon inflation configured to change a thickness of the airbag from a thickened part to a thinned part by a tether coupled to the panels. The tether is divided into a plurality of pieces along a direction in which the panels face each other, and is thus configured by a plurality of divided pieces to be sewn each other at a linear sewing line. A panel-side divided piece sewn to the panel has a wide part, a narrow part and a width-changing part, which correspond to a thickness dimension changed from the thickened part to the thinned part. A panel-side edge of the panel-side divided piece has a shape including a curve part corresponding to the thickness dimension, and is sewn with being overlapped in a planar shape to the panel.