A reactor includes an outer peripheral iron core, at least three iron cores, and a coil wound around the iron core. The reactor further includes an energizing portion connected to the coil and configured to be connected to a cable, and a cover provided to cover the energizing portion. At least one cutout formed in the cover is provided with at least one adjustment member configured to adjust an area of the cutout at least partially in the cover. The adjustment member is configured to be cut away from the cutout or to be bent with respect to a surface where the cutout is formed.