The fixing device

PROBLEM TO BE SOLVED: To provide a fixing device capable of suppressing reduction in calorific power in a position corresponding to a gap between magnetic materials.SOLUTION: A first magnetic material and a second magnetic material for guiding the line of magnetic force of an alternating magnetic field are provided in a coil. A projection part which is smaller than the outer diameter of the first magnetic material and projected in the spiral-axis direction of the coil is provided in the first magnetic material. A recess part which is recessed in the spiral-axis direction of the coil is provided in the second magnetic material. The projection part and the recess part are fitted each other, so that the first magnetic material and the second magnetic material are overlapped with each other in the spiral-axis direction of the coil.SELECTED DRAWING: Figure 7