A starter for cranking an internal combustion engine includes an electric motor, an output shaft, and a one-way clutch for transmitting a rotational torque of the electric motor to the output shaft. The one-way clutch is composed of a clutch-outer driven by the electric motor, a clutch-inner spline-coupled to the output shaft, and rollers disposed between the clutch-outer and the clutch-inner. A portion of the clutch-inner is utilized as an inner ring of a ball bearing rotatably supporting the clutch-inner. A ball-groove rotatably supporting the bearing balls and retaining lubricant therein isformed on the outer circumference of the clutch-inner. In this manner, an original inner ring of the ball bearing can be eliminated without adversely affecting the lubricating function.