STARTER RING GEAR FOR VEHICLE

PROBLEM TO BE SOLVED: To provide a starter ring gear for a vehicle, which can suppress reduction in hardness of outer circumferential teeth which occurs during welding of a drive plate.SOLUTION: The starter ring gear for a vehicle includes a plurality of circumferential direction grooves 94 formed in the circumferential direction of the other side face 90 to be longer than a welding bead 92, which function as heat resisting parts for suppressing conduction of heat of welding with the drive plate 26 to outer circumferential teeth 44a on, between the inner peripheral surface of the starter ring gear 44 and the tooth surface of the outer circumferential teeth 44a, on a plurality of welding parts with the drive plate 26, namely, on the outer circumferential side of the welding bead 92. Thus, since annealing of the outer circumferential teeth 44a of the starter gear 44 increased in hardness by high-frequency hardening welding of the starter gear 44 and the drive plate 26 is suppressed, reduction in hardness of the outer circumferential teeth 44a near the welding part by welding with the drive plate 26 is suppressed.