A reactor including: a coil that includes a winding portion; a magnetic core that includes an inner core portion that is disposed inside the winding portion and an outer core portion that is disposed outside the winding portion; and an outer interposed portion that is interposed between an end surface of the winding portion and an inner end surface of the outer core portion The winding portion includes a winding wire body and a fusing layer that is provided on an outer circumferential surface of the winding wire body and joins turns that are adjacent to each other, and the reactor further includes an adhesion prevention structure configured to prevent the end surface of the winding portion and the outer interposed portion from adhering to each other due to the fusing layer.