To provide a magnetic field heating apparatus for uniformly heating a metal.

For uniformly heating different metallic parts, there is provided a means for generating alternating magnetic field through which the metallic parts are passed. Difference from induction heating of the metallic parts is that parts are uniformly heated not only the surface or the outside of the parts. The heating can be accomplished by providing a new magnetic loop that generates a high density alternating magnetic field to metal parts to be heated.