An airbag device with a horn switch body, configured so as to be installed in an upper surface side in a boss portion near a center of a steering wheel, includes: an airbag which inflates by receiving inflation gas; an inflator for supplying inflation gas to the airbag; a pad covering the folded airbag; a mounting base made of sheet metal which holds the airbag, the inflator, and the pad; a horn switch body having an assembling pin to be assembled to a main body side of the steering wheel; and a support plate made of a sheet metal which supports the horn switch body as a configuration attached to a lower surface side of the mounting base. A case around the assembling pin, the mounting base, or the support plate is provided with a spacer capable of preventing rattling of the switch disposition portion in the case.