A reactor including a magnetic core and a coil having a wound part, the magnetic core having an inner core part disposed inside the wound part and an outer core part disposed outside the wound part, is provided with a bolt coupling the inner core part and the outer core part, the bolt being constituted by a composite material formed by dispersing a soft magnetic powder in a resin and including a shaft part passing through the outer core part, the shaft part including a tip reaching the inner core part, and the inner core part and the outer core part respectively being an integrated member having an undivided structure.