A method for induction surface hardening includes, when in a feed mode, moving an induction coil of a hardening device over a ring surface of a work piece in a treatment direction, to heat the ring surface from an initial zone to a final zone. A sprayer, located downstream of the induction coil in the direction of treatment, is activated to apply quenching liquid to the heated ring surface to both cool and harden the ring surface. An unhardened soft zone is provided between the initial zone and the final zone. A supplementary induction coil, the induction coil and the sprinkler are respectively activated and deactivated separately at the start and end of the hardening, while the relative feed speed between the hardening device and the work piece, and/or the power supplied to each of the supplementary induction coil and the induction coil, are varied at the same time.