A winding structure which is disposed over an armature and a commutator includes an equalizer. The equalizer includes a going portion and a return portion which are wound across one group of teeth through a slot and connected between two identical segments. In a case where an integer number is an expansion value among values which are integer multiples of a value which is acquired by dividing the total number of the slots by the total number of pole pairs, when one group of the teeth having the same total number as the expansion value is given as an element teeth group, the going portion and the return portion are wound across the element teeth group through the slots positioned at both sides of the element teeth group.