KNEE AIRBAG DEVICE

A knee airbag device includes: an airbag case disposed at a lower face part of an instrument panel; a knee airbag accommodated within the airbag case in a folded state, the knee airbag inflating and deploying toward a vehicle rear side and a vehicle upper side upon being supplied with gas; and an airbag door part disposed at a vehicle lower side of the airbag case, the airbag door part having a substantially U-shaped rupture target part, the rupture target part is open toward a vehicle front side as seen in a plan view, at a portion, of a bottom wall part configuring a vehicle lower side face of the airbag door part, disposed rearward of an intermediate part of the airbag door part in a vehicle front-rear direction, and the portion of the bottom wall part disposed rearward of the intermediate part opening toward a vehicle lower side upon rupture of the rupture target part caused by inflation pressure of the knee airbag.