To improve the operability of the horn switch device installed in the air bag apparatus, and to reduce tie manufacturing cost by simplifying its constitution. The air bag apparatus 4 supports the side wall 26b of the cover body 26 to be movable back and forth on the outer periphery of the surrounding wail 24b of the base plate 24. The hook 24b protruding from the surrounding wall 24b is locked onto the lock receiving portion 26h of the side wall 26b, thereby to regulate the moving range of the cover body 26. The bracket 35 is mounted on the under surface of the coverage 26 of the cover body 26 being positioned at each of the spokes 7. The movable contact 36e is mounted on the bracket 35. The fixed contact support portion 31 is provided on the outer peripheral surface of the side wall 26b of the base plate 24 to protrude therefrom, and the fixed contact 31d is provided to oppose the movable contact 36e. The coil spring 38 is provided between the bracket 35 and the fixed contact support portion 31. <IMAGE>
