Airbag apparatus

An automobile airbag apparatus is disposed within an instrument panel covered with an interior cover 21. A fracture-opening section 30 is defined in the interior cover 21 to be located in opposition to an opening portion 22a of an airbag case 22. The fracture-opening section 30 is defined by at least a fragile groove 30a formed from the back surface of the interior cover 21 to surround the fracture-opening section 30. A reinforcement plate member 33 is attached to the back surface of the fracture-opening section 30 through deformation of a portion of the fracture-opening section 30 through application of heat thereto. The reinforcement plate member 33 has a main-body portion 33a attached to the back surface of the fracture-opening section 30 and an attachment portion 35 extending from the main-body portion 33a via a hinge portion 34. A plurality of slits 33b are formed at predetermined intervals in the longitudinal direction of the reinforcement plate member 33 such that the slits 33b extend in parallel in the transverse direction of the reinforcement plate member 33.