Problems to be solved: to provide a coil device and a
magnetic field generating device with reduced
energy loss that are suitable for use in the thermotherapy method.Means for solving the problem: a coil device according to the present invention can be used in a
magnetic field generating device for the thermotherapy method in which a
magnetic flux is irradiated to the patient to selectively heat a specific portion of the patient. Said coil device is a bread-shaped coil device having a current path extending in the shape of a spiral in a substantially same plane, said current path comprising a hollow cylindrical member (10) of a nonmagnetic material inside which a space is formed and a plurality of conductive wires (11, 12) covered with an insulation material on the peripheries thereof. In the present invention, the current path comprising a plurality of conductive wires covered with an insulation material which are arranged in a circle,
energy loss caused by the
skin effect and
energy loss caused by the line capacity can be reduced, making it possible to generate a strong
magnetic field. Also, by using the hollow cylindrical member (10), it is possible to easily configure a current path in a predetermined
diameter and to inhibit increase in temperature of the coil (3) to avoid fluctuation of the
resonance frequency of the
resonance circuit. With this, a magnetic field generating device that is suitable for use in thermotherapy, particularly
cancer therapy, can be realized.