A rolling bearing unit includes: an inner ring member having a recess on a first side in an axial direction along a rotation axis, which is recessed toward a second side in the axial direction; an outer ring member on an outer peripheral side of the inner ring member; a rolling body between the inner ring member and the outer ring member; a non-contact transmitter using electric field coupling capable of transmitting at least one of an electric power or a signal and including a stationary-side transmission part including a stationary-side electrode and a rotary-side transmission part including a rotary-side electrode facing the stationary-side electrode; and a covering member supported by the first side of the outer ring member in the axial direction, covering the first side of the inner ring member in the axial direction, and fixing the stationary-side transmission part to the first side in the axial direction.