An igniter assembly includes: an igniter including a container made of metal and an ignition charge, the igniter being configured to emit a combustion product of the ignition charge to an outside of the container when a lid wall portion is ruptured when the igniter is operated, the container including a peripheral wall portion having a tubular shape and the lid wall portion configured to close one end portion of the peripheral wall portion, the ignition charge being filled in an accommodating space defined by the peripheral wall portion and the lid wall portion; and a tubular wall portion made of resin and formed in a tubular shape in a manner that the peripheral wall portion is surrounded, the tubular wall portion inwardly forming an emitting space in which the combustion product of the ignition charge is emitted. The lid wall portion includes an annular outer peripheral region portion connected to one end portion of the peripheral wall portion and a central region portion positioned inside the outer peripheral region portion in a radial direction compared to the outer peripheral region portion, and the outer peripheral region portion is formed thicker than the central region portion.