The knee-protecting airbag apparatus (M1) includes an airbag (61) folded and housed in a lower area (16a) inside the column cover (16). The airbag (6 1) pushes and opens a door section (34) on the column cover upon deployment. When the door section (34) is thus opened, a door (35) of the door section (34) blocks off an allowance gap (H) formed between an outer circumference ( 18) of the column cover (16) subjected to position adjustment and a lower ar ea (11a) of a peripheral region (11) of an installation opening (10) on a da shboard (7) for installing the column cover (16) by locating a rear edge reg ion (36) of the door (35) to abut on a rear side (12) of the dashboard (7) o r the lower area (11a) of the peripheral region (11) of the installation ope ning (10) on the rear side (12) of the dashboard (7).
