Provided is a small-sized, lightweight, low-cost, and highly reliable bearing device for a driving wheel which needs no tapered spline, and eliminates a circumferential backlash in spline fitting portions to thereby prevent unusual noise. The bearing device for a driving wheel comprises an outer race (5) having an inner periphery in which double-row outer raceway surfaces (13, 14) are formed; a hub wheel (1) and an inner race (2) having outer peripheries in which double-row inner raceway surfaces (7, 8) opposed to the outer raceway surfaces (13, 14) are formed; and double-row rolling elements (3, 4) interposed between the outer raceway surfaces (13, 14) of the outer race (5) and the inner raceway surfaces (7, 8) of the hub wheel (1) and the inner race (2). A shaft hole (28) of the hub wheel (1) is formed into a cylindrical shape, and a male spline (26) is formed on an outer periphery of a stem section (27) of the outer joint member (15) so that the stem section (27) of the outer joint member (15) is press-fit into the shaft hole (28) of the hub wheel (1). With this, recesses caused to closely fit on the male spline (26) with interference are formed in the shaft hole (28) of the hub wheel (1), whereby the hub wheel (1) and the outer joint member (15) are separably coupled to each other.