A bearing unit includes: a housing; a shaft passing through the housing and rotatably supported on the housing; and a pair of rolling bearings disposed between the housing and the shaft and fitted to two positions on the shaft, which are axially spaced apart from each other. At least one rolling bearing has an inner ring press-fitted to the shaft. The inner ring defines an intermediate portion including an inner raceway surface. A reduced diameter part having an outer diameter smaller than the inner diameter of the inner ring and a predetermined width in the axial direction is formed on the shaft at a position corresponding to the intermediate portion so that inner circumferential surfaces located at both ends of the inner ring in the axial direction are interference fitted to the shaft and the inner circumferential surface at the intermediate portion thereof is clearance fitted to the shaft.