Knee airbag device

A knee airbag device for protecting a knee of an occupant, comprising:

• an airbag cushion configured to be stored in front of the knee of the occupant and for expanding and deploying toward the knee side;
• an inflator for injecting expansion gas to expand the airbag cushion;
• a storage case for storing the airbag cushion, in which is formed an opening part through which the airbag cushion that has expanded and deployed by the expansion gas pops out;
• a first flap for covering the airbag cushion exposed through the opening part to transverse in an up-down direction or front-rear direction a center part of the airbag cushion in a lateral direction such that the airbag cushion is retained in the storage case, and having a first weak part that breaks when pressed by the airbag cushion during expansion and deployment;
• and,
• a second flap, which is a component with a larger dimension in a length direction than the first flap, for covering an outer surface of the first flap so as to transverse in the up-down direction or front-rear direction a center part of the airbag cushion in the lateral direction, the second flap having a second weak part between a first end of the second flap and a second end of the second flap, wherein the second weak part breaks when pressed by the airbag cushion after rupture of the first weak part.