PURPOSE: To carry out the scarfing treatment without inspecting flaws generated in the surface of the steel material, by supplying the high-frequency current to the skin layer of the steel material, and by blowing the reducing agent and inert gas at high pressure on purpose to melt and fill the flaw.

CONSTITUTION: The electrodes 2 are pushed tight against the both sides of the raw material 1 whose skin layer is supplied with parallel current from the high- frequency power supply 5; hereupon, the electric resistance at neighborhood of the flaw 8 becomes large so that the surrouding of the flaw 8 is locally heated, molten, and recrystallized. The reducing agent is blown from the high-pressure reducing agent spray 6 at a high presure against the surface of the raw material 1 including above stated molten part, on purpose to prevent the pollution to be caused by atmospheric oxygen and nitrogen, to float the impurity, and to moderate the speed of cooling and solidification. Besides, the high-pressure inert gas is blown against the surface of the raw material, insteatd of or together with this reducing agent. According to this method, whatever kind of flaws can be molten and filled, so that the danger of generation of hair cracks, etc., can be avoided.