To provide an electromagnetic induction heater capable of generating convection even if the heating power is made small.

The electromagnetic induction heater has one control part 56 and a power supply part 10, a set of main inverter part 20 and main work coil 50, and two sets of sub-inverter parts 30, 40 and sub-work coils 51, 52. The main work coil 50 and the sub-work coils 51, 52 are wound in swirl shape and arranged in concentric form, and the inner periphery 51b of the sub-work coil 51 is arranged at the outside of the outer periphery 50a of the main work coil 50, and the inner periphery 52b of the sub-work coil 52 is arranged at the outside of the outer periphery 51a of the sub-work coil 51. The control part 56 drives only the main inverter part 20, or drives the main inverter part 20 and one or more sub-inverter parts 30, 40 synchronously.