Passenger airbag apparatus

A passenger airbag apparatus (12) comprises: an airbag (14) configured to inflate and expand between a panel (10) and a passenger (M) from an opening (10a) provided in the panel (10), the panel (10) constituting an inner wall of a vehicle; a retainer (16) configured to comprise a body (26) having a substantially rectangular bottom surface (26a) and substantially rectangular frame-shaped side walls (26b) and to house the airbag in a folded state; arm members (18) configured to extend respectively from the side walls (26b) along a left and right directions of the vehicle in a state where the retainer (16) is attached to the vehicle, and to be affixed to the panel (10); a substantially disk-shaped gas generator (20) attached to the bottom surface (26a) of the body (26) and configured to supply gas to the airbag; and a support member (22) arranged in a manner that the upper end portion thereof is attached to an outer periphery of the opening (10a) of the panel (10) and to cover the sides of the airbag in the folded state, characterized in that: the retainer (16) further includes hook members (18) provided on the side walls (26b) along a front and rear directions of the vehicle in the state where the retainer (16) is attached to the vehicle, and engage the body (26) with the support member (22) by passing through through-holes (24) provided in the support member (22); the body (26) and the hook members (18) are integrally constructed with substantially the same thickness by extrusion molding; and the hook members (18) further includes a first rib portion (28a).