PURPOSE: To shorten a cutting time by providing on an arbor a plurality of flat milling cutters having cutting parts corresponding to at least the width of a portion to be cut.

CONSTITUTION: A milling cutter 34 has a cylindrical form having the axial dimension approximately equal to the length of a journal part and a plurality of cutting edges 34a on the outer peripheral surface. A cutting unit 30 advances a bed 39 and rotatably drive an arbor 33 in the same direction as a camshaft S, so that the arbor 33, i.e., a milling cutter 34 is moved to the camshaft S with predetermined speed. Thus, the respective milling cutters 34 cut the corresponding journal parts of the camshaft S respectively with the cutting edges 34. Then, patches 55 abut against the camshaft S above and from above and below in the opposite direction to the cutter 34 to regulate the excessive bending, so that the cutting accuracy is prevented from degradation to provide high accuracy working precision.