A coil for forming an induced magnetic field may include a first coil bundle formed of a first conducting wire wound in a first direction, the first coil bundle having an inner space of a prescribed inner width, a second coil bundle formed of a second conducting wire wound in a second direction, the second coil bundle having a prescribed outer width that is smaller than the inner width of the first coil bundle, and a connector that electrically connects the first conducting wire and the second conducting wire to each other. The second coil bundle may be provided in the inner space of the first coil bundle. The conducting wires of the first and second coil bundles may be wound in opposite directions and gaps between coil bundles may be changed. Accordingly, the magnetic field can be more evenly distributed in a wider area while maintaining a constant inductance.