To enable to efficiently heat and cook a hot-pot, etc., by winding a first work coil and an induction coil around inside and outside of an almost cylindrical insulator and flat-spirally winding a second work coil connected to the induction coil around an opening part at the upper side of the insulator.

An induction coil 21 is placed to face a first work coil putting an insulator 11 inside, a second work coil 22 is flat-spirally wound, and the starting and the finishing of the winding are connected between both ends of the induction coil 21. The second work coil 22 is attached to a top plate 23 by a metal fitting. When the first work coil is driven by an invertor power source 17, AC current is induce at the induction coil placed the insulator inside and supplied to the second work coil 22 connected to the secondary side. Eddy current is generated by an AC magnetic field generated at the bottom part of an iron pot 24 put on a top plate 23. As the result, the iron pot is heated by heat generated by eddy current loss.