An airbag unit configured to cover at least a part of a windshield and a front pillar outside of a vehicle, the airbag unit comprising: an airbag formed in a U-shape including a bottom portion (10a, 10b) and a pair of projecting portions projecting from the bottom portion; a gas generator that ejects gas into the airbag; a lower cover unit that accommodates therein the folded airbag and the gas generator; and an upper cover unit that covers the lower cover unit containing therein the airbag, wherein the airbag is expanded by the gas ejected from the gas generator through between a hood of the vehicle and the windshield, characterized in that: the lower cover unit and the upper cover unit each include a recess (21d, 21e, 24c, 24d) for circumventing functional parts of the vehicle, wherein the upper cover unit includes: a cover lid, a flange projecting from the end portion of the cover lid, a first recess and a second recess formed along the first recess and the second recess of the lower cover unit, a groove formed on an upper face of the cover lid and extending in the longitudinal direction thereof and wherein the cover lid is inclined downward toward the groove, and a sloped recess formed in a region of the upper face of the upper cover unit on the side of the forward portion of the vehicle. an airbag formed in a U-shape including a bottom portion (10a, 10b) and a pair of projecting portions projecting from the bottom portion; a gas generator that ejects gas into the airbag; a lower cover unit that accommodates therein the folded airbag and the gas generator; and an upper cover unit that covers the lower cover unit containing therein the airbag, wherein the airbag is expanded by the gas ejected from the gas generator through between a hood of the vehicle and the windshield, characterized in that: the lower cover unit and the upper cover unit each include a recess (21d, 21e, 24c, 24d) for circumventing functional parts of the vehicle, wherein the upper cover unit includes: a cover lid, a flange projecting from the end portion of the cover lid, a first recess and a second recess formed along the first recess and the second recess of the lower cover unit, a groove formed on an upper face of the cover lid and extending in the longitudinal direction thereof and wherein the cover lid is inclined downward toward the groove, and a sloped recess formed in a region of the upper face of the upper cover unit on the side of the forward portion of the vehicle. the lower cover unit and the upper cover unit each include a recess (21d, 21e, 24c, 24d) for circumventing functional parts of the vehicle, wherein the upper cover unit includes: a cover lid, a flange projecting from the end portion of the cover lid, a first recess and a second recess formed along the first recess and the second recess of the lower cover unit, a groove formed on an upper face of the cover lid and extending in the longitudinal direction thereof and wherein the cover lid is inclined downward toward the groove, and a sloped recess formed in a region of the upper face of the upper cover unit on the side of the forward portion of the vehicle. a cover lid, a flange projecting from the end portion of the cover lid, a first recess and a second recess formed along the first recess and the second recess of the lower cover unit, a groove formed on an upper face of the cover lid and extending in the longitudinal direction thereof and wherein the cover lid is inclined downward toward the groove, and a sloped recess formed in a region of the upper face of the upper cover unit on the side of the forward portion of the vehicle.