A fixing device, comprising: a housing; a magnetic flux generation source fixed to the housing and configured to generate a magnetic flux; a first rotary body configured to be rotated in a predetermined direction and induction-heated by the magnetic flux; a second rotary body configured to be rotated in a predetermined direction, a nip portion through which a sheet carrying a toner image passes being formed between the first and second rotary bodies; a first core (54, 56) made of a magnetic material and configured to form, together with the first rotary body, a magnetic path, along which the magnetic flux passes; a second core made of a magnetic material, arranged between the first core and the first rotary body with respect to the magnetic path and rotatable in a predetermined direction; a shaft portion configured to hold the second core on a peripheral surface and serving as a rotary shaft in the rotation of the second core; and a magnetic shielding body made of a nonmagnetic material, arranged on a peripheral surface of the second core or the shaft portion and configured to shield or suppress the magnetic flux by being located in the magnetic path due to rotation about the shaft portion; characterized by the shaft portion having a hollow cylindrical shape, and including an internal space extending along an axial direction inside; an air flow generator configured to generate an air flow flowing in the internal space from one end side toward the other end side in the axial direction; the magnetic flux generation source being fixed to the housing to surround the second core extending in the axial direction when viewed in a direction perpendicular to the axial direction. a housing; a magnetic flux generation source fixed to the housing and configured to generate a magnetic flux; a first rotary body configured to be rotated in a predetermined direction and induction-heated by the magnetic flux; a second rotary body configured to be rotated in a predetermined direction, a nip portion through which a sheet carrying a toner image passes being formed between the first and second rotary bodies; a first core (54, 56) made of a magnetic material and configured to form, together with the first rotary body, a magnetic path, along which the magnetic flux passes; a second core made of a magnetic material, arranged between the first core and the first rotary body with respect to the magnetic path and rotatable in a predetermined direction; a shaft portion configured to hold the second core on a peripheral surface and serving as a rotary shaft in the rotation of the second core; and a magnetic shielding body made of a nonmagnetic material, arranged on a peripheral surface of the second core or the shaft portion and configured to shield or suppress the magnetic flux by being located in the magnetic path due to rotation about the shaft portion; the shaft portion having a hollow cylindrical shape, and including an internal space extending along an axial direction inside; an air flow generator configured to generate an air flow flowing in the internal space from one end side toward the other end side in the axial direction; the magnetic flux generation source being fixed to the housing to surround the second core extending in the axial direction when viewed in a direction perpendicular to the axial direction.