A structure easy processing equipment, and to provide a processing method capable of easily gear or spline shaft machining using existing lathe. And A cutter 11 that is driven to rotate about an axis R1 has a blade portion 20 formed in a ring shape on a peripheral surface, the work holding means 13 for holding rotatably the workpiece W, and the cutter and the workpiece the a cutter drive means 12 for relatively moving in the axial direction, thereby interlocking the rotation of the relative movement and the work of the cutter and the workpiece, to form a gear or spline shaft the peripheral surface of the workpiece while rotating the cutter in the processing apparatus 1, the blade section is more juxtaposed bidirectionally to the axis, the cutter driving means are relatively reciprocated with respect to the workpiece along the cutter axis and the axis is rotated in one direction around the workpiece holding It means the work is rotated normally and reversely in accordance with the reciprocating movement of the cutter, by contacting the respective edge portions of the cutter on the peripheral surface of the workpiece to the cutting to form the outer shape of the gear or spline shaft relative to the workpiece. .FIELD 1