An internal combustion engine has a one-way clutch including a ring gear connected to the output shaft of a starting motor, an outer race member connected to a crankshaft, and a claw piece arranged between the outer circumferential surface of the ring gear and the inner circumferential surface of the outer race member facing the outer circumferential surface of the ring gear. The ring gear and the outer race member have a threaded hole and a through hole, respectively, to receive a jig for fixing the ring gear and the outer race member to each other.