Electromagnetic-induction heater with magnetic field control

An electromagnetic-induction heater having electromagnets which are disposed on both sides of a strip and in face-to-face relationship with each other is disclosed. The electromagnetic-induction heater is arranged to heat by the use of electromagnetic induction the strip which is transferred in a predetermined direction. The electromagnets are respectively constituted by a plurality of magnetic-pole segments which are disposed in a split manner transverse to the direction of travel of the strip and which are capable of individually moving toward the strip, and common coils which surround the magnetic-pole segments. The electromagnetic-induction heater comprises a nonmagnetic-metal movable shielding plate which is disposed at each end portion of each magnet which is near the strip. The shielding plate is moved forward and backward parallel to and transversely relative to the length of the strip, thereby reducing a fringing field generated by each of the magnetic-pole segments.