To provide a one-way clutch device, compact in the radial direction, and capable of restraining functional reduction by abrasion.

This one-way clutch device includes a first clutch member 19, a second clutch member 20, a rolling element 21 rollably arranged between the first clutch member 19 and the second clutch member 20, and a retainer 40 provided with a pocket part 41 for rollably holding the rolling element 21. An inclined face 24 contacting with the rolling element 21 is formed on at least one end surface among opposed end surfaces of the first clutch member 19 and the second clutch member 20, and a step surface 26 is formed between the inclined faces on the end surfaces. An engaging projection part 42 engaging in the circumferential direction with the step surface 26 is arranged in the retainer 40.