Abstract: A transformer includes a leg iron core including a plurality of magnetic sheets stacked in one direction (Z axis direction), and a coil wound around the leg iron core. A slit is formed in at least a magnetic sheet which faces an inner peripheral surface of the coil in a stacking direction of the plurality of magnetic sheets, of the plurality of magnetic sheets. Since eddy current is divided by the slit, eddy current density can be reduced. By reducing the eddy current density, loss density in an iron core can be reduced. By reducing the loss density in the iron core, loss in the transformer can be reduced.