The bearing unit includes a bearing 1 and bearing unit forming component parts such as, for example, a housing 11 in which the bearing is incorporated, a shaft 19, covers 3 and 4 and a sealing member 10 for the housing. In this bearing unit, at least one of the bearing unit forming component parts is fitted with an IC tag 15 and an IC tag 16 is also fitted to the bearing 1. The IC tag 16 fitted to the bearing unit forming component part is of a read/write type whereas the IC tag 16 fitted to the bearing 1 is of a read-only type. The read-only IC tag 16 fitted to the bearing 1 is recorded with information necessary to correlate the bearing unit forming component part, to which the IC tag 15 is fitted, with the bearing unit 1.