An airbag apparatus equipped with an airbag, a garnish, a hinge, a protector and a bracket fixed to a vehicle body. An upper side of the garnish is supported by the bracket via the hinge. An engaging part protruding from the lower part of a garnish main part is engaged with an engagement receiving part disposed at the protector. Normally, the engaging part is engaged with the engagement receiving part, thereby retaining the shape of the garnish. On expansion of the airbag, the airbag presses the engaging part, by which the engaging part is disengaged from the engagement receiving part, and the garnish is opened smoothly. The airbag can be covered with the garnish, thereby allowing the garnish to move smoothly on expansion of the airbag.