To provide an apparatus for accurately and inexpensively processing a winding stem for a timepiece at the high quality and high speed, and manufacturing the winding stem by use of an automatic lathe only.

In a cutting machine for cutting the winding stem for the timepiece and having two main shafts, a workpiece is attached to one main shaft. A cutter is attached to the other main shaft. Two main shafts are driven at a predetermined preset speed. The workpiece is processed so as to form a square shape section in the winding stem. The square shape section can be accurately shaped by processing it by use of only one cutter blade.