AIRBAG APPARATUS

[Object] To provide an airbag unit that can be quickly unfolded, and also retrofitted to an existing vehicle body. [Solution] The airbag unit 20 includes an airbag 10 that covers, upon being unfolded, at least a part of a hood 4 or a windshield 6 outside a vehicle 1, a gas generator 11 that ejects gas into the airbag 10, a cover bottom member 21 that accommodates therein the airbag 10 yet to be expanded and the gas generator 11, a cover lid member 22 including a cover lid plate 22a that covers the cover bottom member 21 in which the airbag 10 is accommodated, and a cowl cover 28 attached to the cover lid plate 22a between the hood 4 and the windshield 6.