A steering wheel body has covering materials for covering a ring core and spoke cores and a pad member integrally formed with the covering materials. An adaptor is fitted to the tip of a steering shaft, the adaptor having an inside serration engaging with the serration of the steering shaft and an outside serration engaging with the serration of a boss member. Moreover, the boss member of a boss plate is provided with a through-hole extending in a direction perpendicular to the axial direction of the steering shaft. A bolt for fastening the adaptor of the steering shaft is screwed into the through-hole.