An airbag device according to the invention is applicable to an airbag device having an airbag that is housed in a state of being able to inflate and deploy in front of an occupant. The airbag has a center chamber positioned in the vicinity of the center on the occupant side in a deployed state, and side chambers positioned on both the left and right sides of the center chamber. Moreover the airbag is provided with a gas supply section that supplies inflation gas to inside of the side chambers, and a means for introducing inflation gas to inside of the center chamber after the side chamber. Furthermore, the side chamber has; a gas introduction space into which inflation gas from the gas supply section is introduced, an upper space that extends upward from the gas introduction space, and a lower space that extends downward from the gas introduction space.