A wheel bearing device includes an inner shaft and an inner ring member fitted onto an outer periphery of an axially-inner end portion of the inner shaft. A shaft portion coupled to the inner shaft so as to be rotatable together with the inner shaft is inserted in a center hole of the inner shaft. Spline grooves spline-fitted to spline teeth formed on an outer periphery of the shaft portion are formed in an inner periphery of the inner shaft, which defines the center hole. An annular clearance that suppresses reduction in a diameter of the inner shaft due to fitting of the inner ring member onto the inner shaft is formed between the inner ring member and the axially-inner end portion of the inner shaft, within a range where an axial range in which the spline teeth are formed overlaps with an axial range of the inner ring member.