A core main body includes an outer peripheral iron core, and at least three iron cores. Between the two iron cores adjacent to each other, a gap being magnetically couplable is formed. The outer peripheral iron core includes a first outer peripheral iron core block and a second outer peripheral iron core block that are formed by stacking a plurality of magnetic plates, and an intermediate plate disposed therebetween. The intermediate plate includes an outer peripheral iron core corresponding portion corresponding to the outer peripheral iron core, a plurality of protruding sections protruding from an outer peripheral surface of the outer peripheral iron core, and engaging sections provided on the plurality of protruding sections.