A compartmentalized airbag knee bolster device is mounted to the instrument panel of a vehicle for restraining forward movement of the knees of the front seat occupants. The device contains a plenum chamber attached to an inflator for pressurizing the plenum chamber. A plurality of airbag compartments are in communication with the plenum chamber by a plurality of one way valves. A knee bolster panel is positioned in front of the plenum chamber with the compartments of the airbag situated therebetween. On inflation of the compartmentalized airbag, the knee bolster panel contacts the front of the knees of a vehicle occupant to restrain forward knee movement. The pressure in the compartments behind the area of the knee bolster panel engaged by the occupant's knees increases in the contacted compartments, and accordingly the rigidity of the airbag in the proximate area of contact with the knees.