An induction heating device and an induction heating method are provided. The entire areas to be heated of the workpiece, even a large workpiece, can be readily and approximately uniformly heated to a predetermined high temperature, and uniform heating is possible even when the workpiece deforms in a non-uniform manner during heating. When areas to be heated H1, H2 are established on a workpiece W so as to extend in one direction and the areas to be heated H1, H2 are induction-heated, the deformation amount on one edge of the areas to be heated H1, H2 is different from that on the other. This induction heating device includes: heating coils 451 facing a portion of the areas to be heated H1, H2 when the workpiece W is induction-heated; and a relative transfer means for transferring the workpiece W and the heating coils 451 along one direction in a relative manner, and the heating coils 451 are disposed so as to correspond to the areas to be heated H1, H2 during the heating period.