PURPOSE: To reduce the number of human judgements and manual operations by mechanizing the selection and the placing of a heating coil body and the setting of quenching condition corresponding to a work in a device for hardening plural kinds of the works at a quenching position in order.

CONSTITUTION: A discriminating device 93 discriminates the work W3 and instructs heating and cooling conditions corresponding to the work W3 to respective high frequency source and jackets 99 and by starting a motor 35, a ball screw 34 is rotated. Then, corresponding to the works w1 to W3, heating coil bodies 100a to 100c on a horizontal rail 36 on the hardening position 101 are shifted through a ball nut 30, and when the coil body 100c comes to a rail ascending part 36a cut-off from the rest part just above the position 101, the motor 35 is stopped. During this time, a cylinder 71 for carrying-in a device 70 is advanced/retreated to place the work W3 to a supporting device 60. Thereafter, the coil body 100c is lowered together with the rail 36 and placed in the work W3, and after energizing the coil, the coil body 100 is ascended. Successively, the cooling water is injected to the work w3 from the jacket 99.