To provide an impact absorbing air bag to hold air in an excellent state in an impact absorbing body without effecting maintenance and inspection for a long period and prevent lowering of impact absorbing ability.

An impact absorbing air bag comprises font and rear boards 1, 2, being vertical to an impact direction; and a hollow bellows-from expandable impact absorbing body 13 located between front and rear bards 11 and 12. The rear board 12 is provided with an air discharge hole 12 extending through the hollow part 131 of the impact absorbing body 13. Thus, since the hollow bellows-form impact absorbing body 13 located between the front and rear boards 11 and 12 is provided, self-reliance of the impact absorbing air bag is practicable. Thereby, even when the hollow part 131 of the hollow bellows- form impact absorbing body 13 is not filled with air, advantages to be usable for a long period are provided.