A gas generator (1A), comprising an igniter (10), a gas generating agent (50) ignited by the igniter (10) and generating gas by burning, and a holder (20) and an AC cup (40) forming therein a gas generating agent storage chamber filled with the gas generating agent (50). A housing formed of the holder (20) and the AC cup (40) is vertically held and fixed by a pair of plate-like members arranged parallel with each other. The gas generator (1A) also comprises projected parts (45) forming deformation areas which deform in a direction for decreasing the vertical outline dimensions of the gas generator (1A) when the housing is fixed by the pair of plate-like members. Thus, when the gas generator (1A) is fixed by the pair of plate-like members in the vertical direction, the dispersion of the outline dimensions of the gas generator (1A) can be absorbed. |