The invention relates to a fixing device with electromagnetic induction heating method that can select whether exerting self-temperature-control function by selecting demagnetizing function, and can set into random high-temperature even if using whole magnetic alloy. Curie point of whole magnetic layer 3C is increased, and magnetic core part 3H and demagnetizing material 3K with semi-cylinder section are set in the inside, demagnetizing material 3K and magnetic core part 3H can rotary in the whole magnetic layer 3C. When increasing demagnetizing material 3K function, the demagnetizing material 3K closes to a coil 2, magnetism of the whole magnetic alloy composed of the whole magnetic layer 3C disappears and becomes non-magnetic body so as to exert high demagnetizing function. When demagnetizing material 3K leaves coil 2, though induction flux generated by the coil 2 permeates the whole magnetic layer 3C, demagnetizing function is not exerted because temperature T of whole magnetic alloy composed of the whole magnetic layer 3C is higher than curie temperature Tc, and magnetism of the whole magnetic alloy does not disappear and is the magnetic body.