To provide a high-frequency induction-hardening apparatus for a rack bar with which a high accurate hardened quality is obtained by utilizing the induction current to a tooth face and a back face of the rack bar and simultaneously and efficiently heating.

The high-frequency induction-hardening apparatus is provided with: a first electrode means composed of one pair of contacting electrodes contacted with at least the tooth face side of the rack bar; a second electrode means disposed at the back face side of the rack bar; and a high-frequency electric source for supplying the high-frequency current to both the electrode means: and the first electrode means and the second electrode means are connected with the above high-frequency electric source under series-state or parallel-state. The above second electrode means is formed of one pair of contacting electrodes contacted with the back face side of the rack bar or high-frequency induction-hardening coils oppositely disposed at the back face side.

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