Patent ID: 7520676

Claim:
A wheel supporting bearing unit comprising: a stationary ring connected to a vehicle body side and comprising: a stationary side peripheral surface; and a stationary side raceway on the stationary side peripheral surface; a rotational member connected to a wheel side and comprising: a rotational side peripheral surface opposing to the stationary side peripheral surface; a rotational side raceway provided on the rotational side peripheral surface, and opposing to the stationary side raceway; and a mounting flange to which a wheel is fixed and which is provided at a part of an outer peripheral surface of the rotational member which lies closer to an axially outer end side; and a cylindrical portion protruded from an axially outer end face of the rotational member; a plurality of rolling elements disposed between the stationary side raceway and the rotational side raceway and an IC chip which is capable of storing information of the wheel supporting bearing unit, wherein the cylindrical portion is provided on a rotational axis of the rotational member and the IC chip directly fixed to an inner face of the cylindrical portion of the rotational member.