An air bag apparatus includes a pad provided with a mounting piece portion extending downwardly from a bottom surface of the pad and having mounting holes. The mounting piece portion is fixed to a side wall of a bag holder in a state in which the mounting piece portion is held between a backplate and the side wall of the bag holder by rivets inserted into the mounting holes of the mounting piece portion and into mounting holes of the side wall of the bag holder and mounting holes of the backplate. Engagement portions for regulating an upward movement of the mounting piece portion are formed at a lower end portion of the mounting piece portion and the backplate except at those portions below the mounting holes. The engagement portions are formed to be recesses and projections which are adapted to engage are another.
