PURPOSE: To shorten the work time following the change of kinds of derivatives by dropping and applying triazinethiol derivatives to wire between the final die outlet in steel wire drawing processing and a winder before rapidly heating the wire surface.

CONSTITUTION: Steel wire 1 which is drawn out by a wiredrawer is twisted into a steel cord 2 by a twister 11. The steel cord 2 passes through cloth 12 annularly provided and a rapid heater 15 successively and wound on a winder 16. At this time, when the steel cord 2 passes through the cloth 12, solution of triazineithiol derivatives to improve the corrosion resistance and adhesive property between wire and rubber is dropped into the steel cord 2 from a tank 13 through the cloth 12. On the other hand, excess solution is received by a container 14. The steel cord 2 is rapidly heated by the rapid heater 15 to accelerate the reaction of the derivatives, causing the work time following the change of kinds of the derivatives to be shortened.