Abstract: Provided are an airbag and an airbag device, which can reduce a pressure loss while the airbag is being inflated and expanded and which can exhibit the shock absorbing force of the airbag device efficiently according to the physical features of a passenger. The airbag device comprises a gas generator for generating a gas under a predetermined condition, an airbag connected to the gas generator so that it is inflated and expanded, and a retainer for housing the airbag. This airbag includes bulges for forming externally protruded portions at the portions of the airbag, vent holes formed in the bulges, straps connected at their one-ends to the bulges and at their other ends to the inside of the airbag, and through holes for guiding the other ends of the straps into the inside of the airbag. The vent holes are arranged at such regions in the bulges that the bulges and the airbag do not overlap when the bulges are pulled by the straps.