PURPOSE: To enhance the installing accuracy of an air bag lid, ensure the expanding performance of the air bag lid reconcilably and improve the appearance of a parting part between the air bag and an opening part.

CONSTITUTION: In an air bag lid 8, a welded bolt 11, which is projected almost perpendicular to an upper surface part 1a of an installment panel 1 at the front and lower surface of the lid 8, is inserted into a bolt inserting hole 16 of a shelf-like flange part 7a and fixed/fastened by a nut 18. A lid lock 24 is fixed to a bracket 21 and engaged with a locking hook 15 after the installation of the air bag lid 8. In addition, the center line of a hook entering port 25a is coincided with the tengential direction of a locus (a) of rotating motion of the locking hook 15, and the bracket 21 is fixed to a boss part 22 on the back surface of the installment panel 1 by using a machine screw 23.