PURPOSE: To facilitate positioning of an inflator bolt to a case bolt hole so as to speelily and smoothly assemble an air bag case and an inflator, in an air bag device in which bolt holes for insertion of stud bolt as well as an insertion hole in which an inflator top is fitted are respectively provided at opposite walls of an air bag case.

CONSTITUTION: While a fitting hole 13 is bored in an end of a stud bolt 10 a guiding rod 15 equipped with a tapered end type fitting pin 14 at its tip is extended out of a case through an insertion hole 7 from a bolt hole 12 of an air bag case 1. The fitting pin 14 of a rod 15 is fitted in the fitting hole of the stud bolt 10 and a stud bolt of an inflator 4 is fitted in the bolt hole 12 of the case 1 with the rod 15 guiding it.