INDUCTION HEATING COOKING APPARATUS

PROBLEM TO BE SOLVED: To improve heating efficiency and prevent dielectric breakdown of a heating coil by forming a litz wire into a multistep lap twisting structure, in which twisted strands are twisted together furthermore, and specifying a volume ratio or more of a strand covered with an insulating layer of the litz wire to the volume of the whole heating coil. SOLUTION: In construction of a litz wire 5, 40 strands are bundled and twisted together at once in primary stranding, two bundles formed in the primary stranding are twisted together in secondary stranding, and four bundles formed in the secondary stranding are twisted together in tertiary stranding. In a heating coil 2 constructed by winding up the litz wire 5, when a volume ratio (a space factor) of the strand (including its insulating layer) to the whole dimension of the heating coil 2 is increased, the stands are bound to each other densely and an inductance is increased, so that electromagnetic coupling with a pot 1 is increased. That is, a high frequency current and the pot 1 are brought closer to each other and electromagnetic coupling is increased, and heating efficiency can be improved. Especially, high heating efficiency can be accomplished when the space factor is set to be 40% or more.