A cover body of a vehicle air bag apparatus, being comprised of a covering portion which is formed integrally with an interior panel body and which has a door portion defined by a tear seam formed in a back of the interior panel body, and, a backing portion joined to a back of the covering portion. The covering portion is made of polyolefin resin having a flexual elastic modulus of from 1500 to 3500 MPa, a tensile strength of from 17 to 40 MPa, an Izod impact strength of from 3.0 to 15.0 kJ/m2, and an elongation of 400% or less. The backing portion is made of thermoplastic olefin which is softer and has a greater elongation. The backing portion is comprised of a reinforcing portion at a back of the door portion, a surrounding base at the back of the covering portion, and a hinge portion joining the reinforcing portion and the surrounding base.