A vehicle wheel bearing apparatus has an outer member and an inner member. Double row rolling elements are freely rollably contained between the outer and inner raceway surfaces of the outer and inner members, via cages. Seals are mounted between the outer and the inner members. A backup seal is fit onto the outer circumference of the outer side end of the outer member. The backup seal has a metal core that includes a cylindrical fitting portion and an upstanding portion that extends radially outward from the fitting portion. A sealing member is integrally adhered to the metal core. The sealing member has a side lip formed so that it extends radially outward from the metal core and inclines toward the inner side surface of the wheel mounting flange to slidably contact the flange, via a predetermined interference.