A rolling bearing unit comprising: an inner ring member having a first recess on a first side in an axial direction along a rotation axis and a second recess on a second side opposite to the first side in the axial direction, the first recess being recessed toward the second side in the axial direction, the second recess being recessed toward the first side in the axial direction and having an opening in the second side of the axial direction, the first recess and the second recess being next to each other in the axial direction with a partition wall disposed therebetween; an outer ring member disposed on an outer periphery side of the inner ring member; a rolling body disposed between the inner ring member and the outer ring member and rotatably supporting the inner ring member with respect to the outer ring member; a transmitter being a contact transmitter including a stationary-side transmission part and a rotary-side transmission part, the transmitter being capable of transmitting at least one of electric power or a signal between the stationary-side transmission part and the rotary-side transmission part, at least a part of the transmitter being accommodated inside the first recess of the inner ring member; a first covering member that is supported by the first side of the outer ring member in the axial direction, covers the first side of the inner ring member in the axial direction, and fixes the transmitter; a second covering member that is fitted in the opening of the second recess, the second covering member including a substrate; a connection plate having an insertion hole in a center of the connection plate in the vertical direction; a first wire; and a second wire, wherein the stationary-side transmission part is connected to the second wire, the rotary-side transmission part is connected to the first wire that is connected to the substrate of the second covering member in the second recess, and the rotary-side transmission part has an outer shape corresponding to the inner peripheral edge of the insertion hole, thereby allowing the first wire and the rotary-side transmission part to be inserted in the insertion hole of the connection plate, fastening the rotary-side transmission part to the partition wall, and allowing the rotary-side transmission part and the connection plate to integrally rotate. an inner ring member having a first recess on a first side in an axial direction along a rotation axis and a second recess on a second side opposite to the first side in the axial direction, the first recess being recessed toward the second side in the axial direction, the second recess being recessed toward the first side in the axial direction and having an opening in the second side of the axial direction, the first recess and the second recess being next to each other in the axial direction with a partition wall disposed therebetween; an outer ring member disposed on an outer periphery side of the inner ring member; a rolling body disposed between the inner ring member and the outer ring member and rotatably supporting the inner ring member with respect to the outer ring member; a transmitter being a contact transmitter including a stationary-side transmission part and a rotary-side transmission part, the transmitter being capable of transmitting at least one of electric power or a signal between the stationary-side transmission part and the rotary-side transmission part, at least a part of the transmitter being accommodated inside the first recess of the inner ring member; a first covering member that is supported by the first side of the outer ring member in the axial direction, covers the first side of the inner ring member in the axial direction, and fixes the transmitter; a second covering member that is fitted in the opening of the second recess, the second covering member including a substrate; a connection plate having an insertion hole in a center of the connection plate in the vertical direction; a first wire; and a connection plate having an insertion hole in a center of the connection plate in the vertical direction; a first wire; and a second wire, wherein the stationary-side transmission part is connected to the second wire, the rotary-side transmission part is connected to the first wire that is connected to the substrate of the second covering member in the second recess, and the rotary-side transmission part has an outer shape corresponding to the inner peripheral edge of the insertion hole, thereby allowing the first wire and the rotary-side transmission part to be inserted in the insertion hole of the connection plate, fastening the rotary-side transmission part to the partition wall, and allowing the rotary-side transmission part and the connection plate to integrally rotate.