A driving wheel supporting rolling bearing unit comprising: a stationary side bearing ring member supported and fixed to a suspension device to be non-rotatable; a rotation side bearing ring member configured to rotate together with a vehicle wheel while supporting and fixing the vehicle wheel; a plurality of rolling elements rollably provided between peripheral surfaces of the stationary side bearing ring member and the rotation side bearing ring member which face each other; a rotation side flange provided on a part of the rotation side bearing ring member and configured to support and fix the vehicle wheel; an internal gear fixed to the rotation side flange and configured to rotate together with the rotation side flange so as to configure a reduction gear , wherein the rotation side bearing ring member is rotationally driven based on a driving force input through the internal gear , characterized by an electric generator including a stator supported by the stationary side bearing ring member and a rotor supported by the rotation side bearing ring member , and configured to generate electric power based on relative rotation between the stator and the rotor ; and a wireless communication device configured to wirelessly communicate with an electronic equipment disposed on a vehicle body side, the electric generator and the wireless communication device being disposed in an accommodating space at an axially inner side of the rotation side bearing ring member , wherein an axially inner end opening of the stationary side bearing ring member is covered by a cover formed of a radio wave permeable material, and a space inside the cover is the accommodating space . a stationary side bearing ring member supported and fixed to a suspension device to be non-rotatable; a rotation side bearing ring member configured to rotate together with a vehicle wheel while supporting and fixing the vehicle wheel; a plurality of rolling elements rollably provided between peripheral surfaces of the stationary side bearing ring member and the rotation side bearing ring member which face each other; a rotation side flange provided on a part of the rotation side bearing ring member and configured to support and fix the vehicle wheel; an internal gear fixed to the rotation side flange and configured to rotate together with the rotation side flange so as to configure a reduction gear , wherein the rotation side bearing ring member is rotationally driven based on a driving force input through the internal gear , characterized by an electric generator including a stator supported by the stationary side bearing ring member and a rotor supported by the rotation side bearing ring member , and configured to generate electric power based on relative rotation between the stator and the rotor ; and a wireless communication device configured to wirelessly communicate with an electronic equipment disposed on a vehicle body side, the electric generator and the wireless communication device being disposed in an accommodating space at an axially inner side of the rotation side bearing ring member , wherein an axially inner end opening of the stationary side bearing ring member is covered by a cover formed of a radio wave permeable material, and a space inside the cover is the accommodating space . <EOS>