A wheel bearing device at low cost with higher durability is provided. An outer joint member of a constant velocity joint is fitted to an inner periphery of a wheel hub, and the outer joint member and the wheel hub are united by plastic deformation in radially outward direction of a stem part of the outer joint member. The outer joint member is made of a steel material chiefly comprising iron, 0.5 to 0.7 weight % of carbon, 0.1 to 1.5 weight % of silicon, 0.6 to 1.0 weight % of manganese, and inevitable impurities.