A knee-protecting airbag apparatus is mountable on a door of a glove box that has a box body provided with an opening at the rear and the door. The airbag apparatus includes an airbag, a generally columnar inflator housed in the airbag, a case housing the airbag and inflator, and an airbag cover constituting a rear face of the glove box door and being openable at airbag deployment. The inflator includes a body that discharges inflation gas and a fixing section that secures the body and the airbag to the case. The fixing section includes a projecting portion and the projecting portion extends at an upward or downward angle to the thickness direction of the glove box door.