PURPOSE: To improve the working efficiency and largely reduce the manufacturing cost by continuously forming anti-corrosion coating on the surface of a metallic linear body for continuous cutting, and performing finishing work by means of barrel polishing.

CONSTITUTION: A metallic linear body 1 collected in the form of a coil bundle is delivered from a delivery machine 2, bending is removed by a correcting device 3, heat treatment is performed through a heat treatment furnace 4 to desired hardness. Then, pre-treatment, such as electrolytic pickling, alkali cleaning, washing, is carried out in a pre-treatment bath 5, a corrosion resistant coating film is formed in a plating bath 6, and the processed part is cut to a desired length by a cutting machine 7 to make a cut shaft 8. Besides, a finish polishing process is applied to the edge surface and the surface of the cut shaft 8 by a barrel polishing device 9 to obtain a motor shaft 10 for toy. It is thus possible to obviate transportation and work between the respective processes, and devices between the respective processes are obviated, and further the working efficiency is largely improved while the manufacturing cost is reduced.