An airbag system includes belt support members for housing support belts used for coupling an airbag to a vehicle body, and belt covers disposed over the belt support members. A central cover panel on the vehicle body is adjacent to an airbag module in which an airbag is accommodated. Left and right cover panels are engaged with, and disposed laterally outside of the central cover panel in the vehicle-width direction. The belt support members are configured by overhanging parts of the central cover panel, which are overhung laterally outside, and extension parts of the cover panels and which extend laterally inside; and both of these components are engaged with each other through engaging portions in the belt support members. Notches are provided in the extension parts, extending in a longitudinal direction of the vehicle body outside in the vehicle-width direction relative to the engaging portions.