Provided is a reactor having high joining strength between an end surface connecting member and an outer resin-molded portion and excellent reliability. A reactor includes a coil having a winding portion, a magnetic core having an inner core portion disposed inside the winding portion and an outer core portion disposed outside the winding portion, an end surface connecting member that is fixed to an end portion of the inner core portion and disposed between an end surface of the winding portion and the outer core portion, and an outer resin-molded portion that integrates the outer core portion and the end surface connecting member, wherein a detachment preventing portion is formed in the end surface connecting member, the detachment preventing portion being embedded in the outer resin-molded portion and having a detachment preventing shape that suppresses detachment of the outer resin-molded portion.