A bearing unit for driving wheels, and a manufacturing method thereof, includes a hub, a bearing, and a constant velocity universal joint, such that a process for assembling the bearing unit to a knuckle member is simplified. In order to achieve this, a hub (10) and an outer joint member (31) of an out-board side constant velocity universal joint (30) are plastically joined together. An outer peripheral surface (26a) of an outer member (26) is press-fitted into an inner peripheral surface of the knuckle member, and a maximum diameter dimension (D1) of the out-board side constant velocity universal joint (30) is set smaller than a minimum diameter dimension (Dn) of the knuckle member (6). Also, a maximum diameter dimension (D2) of an in-board side constant velocity universal joint (40) is set smaller than the minimum diameter dimension (Dn) of the knuckle member (6).