PURPOSE: To avoid generation of dispersion of clearance accompanying unitization between the cam face of a clutch outer ring and needle rollers.

CONSTITUTION: The outer diameter flange part 2a2 of a clutch outer ring 2a is fitted to the inside of the inner diameter flange part 5a2 of a bearing housing 5, the recessed part 2a3 and the claw part 5a3 are adapted to each other capably of being engaged with each other through clearances S4, S5 in the rotational direction, and hence the clutch outer ring 2a and the bearing housing 5 are engaged in one body with each other. The assembly of the rollers 2b received in the clutch outer ring 2a and the retainer 2c is regulated so as not to slip out to both sides in the axial direction, by means of the inner diameter flange part 2a4 of the clutch outer ring 2a and the claw part 5a3 of the bearing housing 5. Further this unit is provided with the clearance S1 in the axial direction between the outer diameter flange part 2a2 and the inner diameter flange part 5a2, the clearance S2 in the axial direction between the outer diameter flange part 2a2 and the rolling bearing 3, and the radial clearance S3 between the inner diameter flange part 5a2 and the outer diameter of the clutch outer ring 2a.