PURPOSE: To provide a quenching method of a chip saw base metal of circular saw and an apparatus therefor, in which the quenched strain of the base metal is restrained to the min., and also, the production of scale can be prevented.

CONSTITUTION: After abutting at least one pair of annular electrodes 4, 6 having a prescribed width and smaller diameter than the outer diameter of the base metal 15 on both side surfaces of the base metal 15, high-frequency current is supplied to the electrodes 4, 6 to electrically heat and quench a prescribed range of the base metal 15. Further, after supplying inert gas in the abuting part between the electrodes and the base metal, the high-frequency current may be supplied to electrically heat the part. One pair of electrodes may be mutually different on both side surfaces of the base metal.