PURPOSE: To reduce the number of parts and improve the easiness of assembly, by dividing the driven part of a one-way clutch into at least 2 parts.

CONSTITUTION: The one end of an approximately cylindrical clutch inner 3b, serving as a driven part and having stages on the inner and the outer peripheral surface, is inserted into the inside of a clutch 5, and the clutch inner 3b is rotatably and also axially slidably fitted around a rotary shaft 2 through the medium of a bearing 7. A pinion gear 6 is axially slidably fitted around a small size part, positioned on opposite side of a large size part side brought into slide contact with a one-way clutch 5, of the clutch inner 3b, through the medium of a second helical spline 4b having the same spiral direction as that of a first helical spline 4a. Division of the driven part of the one-way clutch device into two parts of the clutch inner 3b and the pinion gear 6 can facilitate manufacture of those parts.