Referring to FIG. 2, the heating magnetic body 20 has a structure in which the flat plate-shaped sheet members 21 and the corrugated plate-shaped sheet members 22 are alternately stacked, whereby the plurality of flow paths 23 extending rectilinearly from the inlet-side opening 10i toward the exit-side opening 10e of the tubular insulating member 10 are arrayed. Therefore, pressure loss in the fluid can be reduced, and, due to the shape substantially uniform in the direction in which magnetic lines of force of the electromagnetic induction coil 25 pass (the center axis direction of the tubular insulating member 10), local heat generation is prevented, and the fluid can be efficiently heated.

The direction in which the flow paths 23 extending rectilinearly from the inlet-side opening 10i toward the exit-side opening 10e of the tubular insulating member 10 are directed in the heating magnetic body 20 is not parallel to, but has a slight angle relative to, the center axis of the cylinder of the outline shape of the heating magnetic body 20. Therefore, the rectilinear flow paths having a slight angle relative to the center axis of the cylinder of the outline shape of the heating magnetic body 20 can be set longer than the length in the center axis direction (longitudinal width) of the outline shape, whereby the fluid can be heated more. In addition, by reducing the longitudinal width of the heating magnetic body 20, the longitudinal width of the electromagnetic induction heating apparatus 1 can be reduced, and the size of the electromagnetic induction heating apparatus 1 can be reduced.