A heating apparatus includes a core; magnetic flux generating means having
an excitation coil provided outside the core; an induction heat
generating element for electromagnetic induction heat generation using
the magnetic flux generated by the magnetic flux generating means, a
heating portion for receiving a recording material and for heating the
recording material by the heat generated by the induction heat generating
element, the heating portion being elongated in a longitudinal direction
crossing with a direction in which the recording material is fed to the
heating portion; magnetic flux adjusting means for changing a
distribution, in the longitudinal direction, of densities of the magnetic
flux generated by the magnetic flux generating means in the heating
portion; the magnetic flux adjusting means including a magnetic flux
shield member, and moving means for moving the magnetic flux shield
member to a position for adjusting the magnetic flux generated by the
magnetic flux generating means, the magnetic flux shield member being
effective to block the magnetic flux at a position between the core and
the excitation coil.