Abstract: A pair of pinching members pinching a workpiece stem portion, and a deburring tool performing deburring onto the workpiece stem portion pinched by the pair of pinching members are disposed under a pair of guide rails. The deburring tool has a recess so that an opening of the recess faces the other end face of the workpiece stem portion, and is capable of a displacement motion in an axis extension direction of the recess while rotating around the recess axis, and a recess inner circumferential surface is formed so as to reduce its diameter as it goes from the recess opening side toward a recess internal side, and a blade portion is provided on the recess inner circumferential surface. Thereby, it is possible to perform deburring without increasing the machining line length, and prevent abnormal wear of a rubbing stone due to the deburring.