PURPOSE: To make it possible to form an abrasion-resistant metal film on the surface of a blade without exposing it to high temperatures directly by blowing reactive gas in vaporized gas of abrasion-resistant metal, and applying gas after reaction of both gases to be solidified on the surface of the blade.

CONSTITUTION: A power source is connected between a pair of electrodes A, B consisting of abrasion-resistant metal rods, and they are contacted instantaneously and then pulled apart, so an arc current R is produced, where a blade 4 is enclosed by vaporized gas of abrasion-resistant metal. If reactive gas G is blown to the arc R simultaneously at this time, the vaporized gas and the reactive gas G react to generate heat, and gas particles after reaction are attached to the surface to be liquid, where it radiates latent heat by hardening and attaches to the surface of the blade 4, while forming a thin film of the abrasion-resistant metal. The attachment property and quantity are good. It is vaporized abrasion-resistant metal, not the whole body of a tool, that is exposed to high temperatures instantaneously, so deformation of a base plate 2 of a saw 1 by high temperatures or fusing of blazing of the base 2 and the blade 4 can be prevented.