Fixing device employing electromagnetic induction heating system capable of effectively using magnetic flux and image forming apparatus with fixing device

A fixing device comprises a fixing member having a heat generation layer, an excitation coil disposed opposite an outer circumferential surface of the fixing member to cause the fixing member to induce electromagnetic heat, and a magnetic core to form a continuous magnetic path guiding a magnetic flux generated by the excitation coil to the fixing member. A holder is provided to accommodate and hold the excitation coil and the magnetic core. A first core included in the magnetic core and is arranged opposite the outer circumferential surface of the fixing member not via the excitation coil along a line extended from an axis of the fixing member in a radius direction. An end face of the first core arranged opposite the outer circumferential surface of the fixing member is substantially perpendicular to the line.