Abstract: The present invention disclosed herein relates to a treatment device using a magnetic field, which includes a coil generating a pulse magnetic field and a plurality of cooling structures. In accordance with an embodiment of the present invention, a treatment device using a magnetic field includes: a magnetic field generating coil disposed below a close contact surface that closely contacts a portion of a body; a first blower and a second blower disposed symmetrically with respect to the magnetic field generating coil to supply a fluid toward the magnetic field generating coil; and a duct that provides a seated surface on which the magnetic field generating coil is seated and guides the fluid supplied from the first blower and the second blower toward the magnetic field generating coil, and the duct includes an opening formed by opening at least a portion of an area forming the seated surface.