A reactor includes a coil body, an exterior case, and a filler. The coil body includes a core and a coil wound around the core. The exterior case includes a metal structure and a resin frame. The metal structure has a bottom surface and a side wall provided to stand upright from the bottom surface. The bottom surface and the side wall of the metal structure are unitarily formed with each other. The frame is disposed at an opposite side to the bottom surface of the metal structure. The exterior case houses the core and the coil. The filler is filled between the exterior case and the coil body.