A fixing device includes a pressure member, a heating member, a coil, a first magnetic core, a second magnetic core, a shielding portion, and a switching belt. The second magnetic core is disposed to extend in a width direction in a hollow portion formed by the loop of the coil, and formed in an arc shape with a protruding portion at a side facing the heating member. The shielding portion is formed of a non-magnetic material to shield a path of a magnetic flux generated by the coil between the second magnetic core and the heating member. The switching belt includes a surface where the shielding portion is disposed to face a non-paper passing region in the heating member, suspended to be rotatable between a roller and the protruding portion, and selectively arranged in one of a shielding position and a non-shielding position by rotation of the roller.