a magnetizing method for tone wheel and apparatus , wherein the method comprises the steps of preparing a ring reinforcement made of magnetic material and attached to an annular body to be magnetized , the ring reinforcement comprising a tubular part and an other part integrally formed with the tubular part ; holding the tubular part of the ring reinforcement with a fixing means such as a jaw type chuck means made of non - magnetic material ; and apply an alternate magnetic flux to the annular body while axially rotating the fixing means , keeping one end of a magnetizing yoke approximate to the surface of the annular body , the alternate magnetic flux forming a circular closed loop which passes the one end of the magnetizing yoke and the other end of the magnetizing yoke , via the annular body and the ring reinforcement midway , thereby magnetizing the annular body in a manner that s poles and n poles are alternately formed along its periphery .