An induction heating apparatus for heating a metal plate comprising: an induction coil arranged to surround the metal plate; a front surface side conductor, which is a part of the induction coil, placed on a front surface side of the metal plate; a back surface side conductor, which is a part of the induction coil, placed on a back surface side of the metal plate and connected to the front surface side conductor; and wherein the front surface side and back surface side conductors (2a, 2b) are arranged to be deviated in the lengthwise direction of the metal plate in the central portion of the metal plate in the widthwise direction thereof; and, at least at either edge portion of the metal plate in the widthwise direction thereof, at least one of the front surface side and back surface side conductors (2a, 2b) is arranged to be slanted relative to the widthwise direction of the metal plate in the plan view, or the front surface side and back surface side conductors (2a, 2b) are arranged to be at least partly overlapped in the lengthwise direction of the metal plate in the plan view; characterized in that the apparatus further comprises: a magnetic core arranged from the front surface side over to the back surface side of the metal plate bestriding an edge portion of the metal plate; the magnetic core being arranged on the outer side of the slanted portion of the conductor or on the outer sides of a portion of the conductor that is connecting the central portion of the conductor with the at least partly overlapped edge portion of the conductor in the plan view, wherein the magnetic core produces flows of magnetic flux through the metal plate from the front or back surface to the opposite surface, the flows of the magnetic flux canceling minor loops of a current formed together with a passage of an induced current corresponding to a shape of arrangement of the front surface side and back surface side conductors (2a, 2b) and induced at an outer side of the front surface side and back surface side conductors (2a, 2b). an induction coil arranged to surround the metal plate; a front surface side conductor, which is a part of the induction coil, placed on a front surface side of the metal plate; a back surface side conductor, which is a part of the induction coil, placed on a back surface side of the metal plate and connected to the front surface side conductor; and wherein the front surface side and back surface side conductors (2a, 2b) are arranged to be deviated in the lengthwise direction of the metal plate in the central portion of the metal plate in the widthwise direction thereof; and, at least at either edge portion of the metal plate in the widthwise direction thereof, at least one of the front surface side and back surface side conductors (2a, 2b) is arranged to be slanted relative to the widthwise direction of the metal plate in the plan view, or the front surface side and back surface side conductors (2a, 2b) are arranged to be at least partly overlapped in the lengthwise direction of the metal plate in the plan view; characterized in that the apparatus further comprises: a magnetic core arranged from the front surface side over to the back surface side of the metal plate bestriding an edge portion of the metal plate; the magnetic core being arranged on the outer side of the slanted portion of the conductor or on the outer sides of a portion of the conductor that is connecting the central portion of the conductor with the at least partly overlapped edge portion of the conductor in the plan view, wherein the magnetic core produces flows of magnetic flux through the metal plate from the front or back surface to the opposite surface, the flows of the magnetic flux canceling minor loops of a current formed together with a passage of an induced current corresponding to a shape of arrangement of the front surface side and back surface side conductors (2a, 2b) and induced at an outer side of the front surface side and back surface side conductors (2a, 2b). a magnetic core arranged from the front surface side over to the back surface side of the metal plate bestriding an edge portion of the metal plate; the magnetic core being arranged on the outer side of the slanted portion of the conductor or on the outer sides of a portion of the conductor that is connecting the central portion of the conductor with the at least partly overlapped edge portion of the conductor in the plan view, wherein the magnetic core produces flows of magnetic flux through the metal plate from the front or back surface to the opposite surface, the flows of the magnetic flux canceling minor loops of a current formed together with a passage of an induced current corresponding to a shape of arrangement of the front surface side and back surface side conductors (2a, 2b) and induced at an outer side of the front surface side and back surface side conductors (2a, 2b).