A thrust magnetic bearing device comprising: a thrust disc fixed to a rotating body; and a pair of electromagnets provided so as to sandwich the thrust disc and be spaced apart from the thrust disc in a direction along a rotation axis, wherein: each of the pair of electromagnets includes a coil wound around the rotation axis of the rotating body and a ring-shaped core accommodating the coil; the core includes an outside outer peripheral surface that is a radially outer surface, an outside inner peripheral surface that is a radially inner surface, an outside opposing surface opposed to the thrust disc, an outside non-opposing surface located at an opposite side of the outside opposing surface in the direction along the rotation axis, an inside outer peripheral surface opposed to a radially outer surface of the coil, an inside inner peripheral surface opposed to a radially inner surface of the coil, an inside opposing surface opposed to a surface of the coil, the surface of the coil being located close to the thrust disc, and an inside non-opposing surface located at an opposite side of the inside opposing surface across the coil; the core includes a slit which is located at at least one circumferential position of the core and extends from the outside outer peripheral surface as a starting point toward a center of the core; and wherein the slit is formed in a range including the inside outer peripheral surface and the inside non-opposing surface. a thrust disc fixed to a rotating body; and a pair of electromagnets provided so as to sandwich the thrust disc and be spaced apart from the thrust disc in a direction along a rotation axis, wherein: each of the pair of electromagnets includes a coil wound around the rotation axis of the rotating body and a ring-shaped core accommodating the coil; the core includes an outside outer peripheral surface that is a radially outer surface, an outside inner peripheral surface that is a radially inner surface, an outside opposing surface opposed to the thrust disc, an outside non-opposing surface located at an opposite side of the outside opposing surface in the direction along the rotation axis, an inside outer peripheral surface opposed to a radially outer surface of the coil, an inside inner peripheral surface opposed to a radially inner surface of the coil, an inside opposing surface opposed to a surface of the coil, the surface of the coil being located close to the thrust disc, and an inside non-opposing surface located at an opposite side of the inside opposing surface across the coil; the core includes a slit which is located at at least one circumferential position of the core and extends from the outside outer peripheral surface as a starting point toward a center of the core; and wherein the slit is formed in a range including the inside outer peripheral surface and the inside non-opposing surface. each of the pair of electromagnets includes a coil wound around the rotation axis of the rotating body and a ring-shaped core accommodating the coil; a coil wound around the rotation axis of the rotating body and a ring-shaped core accommodating the coil; the core includes an outside outer peripheral surface that is a radially outer surface, an outside inner peripheral surface that is a radially inner surface, an outside opposing surface opposed to the thrust disc, an outside non-opposing surface located at an opposite side of the outside opposing surface in the direction along the rotation axis, an inside outer peripheral surface opposed to a radially outer surface of the coil, an inside inner peripheral surface opposed to a radially inner surface of the coil, an inside opposing surface opposed to a surface of the coil, the surface of the coil being located close to the thrust disc, and an inside non-opposing surface located at an opposite side of the inside opposing surface across the coil; an outside outer peripheral surface that is a radially outer surface, an outside inner peripheral surface that is a radially inner surface, an outside opposing surface opposed to the thrust disc, an outside non-opposing surface located at an opposite side of the outside opposing surface in the direction along the rotation axis, an inside outer peripheral surface opposed to a radially outer surface of the coil, an inside inner peripheral surface opposed to a radially inner surface of the coil, an inside opposing surface opposed to a surface of the coil, the surface of the coil being located close to the thrust disc, and an inside non-opposing surface located at an opposite side of the inside opposing surface across the coil; the core includes a slit which is located at at least one circumferential position of the core and extends from the outside outer peripheral surface as a starting point toward a center of the core; and wherein the slit is formed in a range including the inside outer peripheral surface and the inside non-opposing surface.