PURPOSE: To allow the easy correction of the bend of a rack after hardening and to prevent cracking to be generated at this time by providing a rack escaping means in the above hardening device to decrease the pressing force of rack retaining members.

CONSTITUTION: The above high-frequency hardening device is formed of two coil end contactors 3, a hardening coil 4 and cooling means 7 provided therebetween, rack retaining means 6, etc. The above-mentioned contactors 3 are fixed at the spacing fitting to both ends of the tooth parts 1 of the rack 1. The above-mentioned rack retaining means 6 press the rack 1 imposed with both ends of the tooth parts 1a on the above-mentioned contactors 3 by lowering the two rack retaining members 5. The rack escaping means 17 is provided on the above-mentioned rack retaining means 6 to decrease the pressing force of the rack retaining members 5.