A reactor 1α includes a coil 2 formed by winding a wire 2w, a magnetic core 3 that is disposed inside and outside of the coil 2 and forms a closed magnetic circuit, and a case 4 that has an opening portion and a bottom surface 40 that opposes the opening portion and that houses an assembly 10 of the coil 2 and the magnetic core 3. At least the opening portion of the case 4 side of the magnetic core 3 is formed of a molded solid body that contains magnetic powder and resin. A surface layer 5, which prevents the magnetic powder from rusting, is provided on a surface of the magnetic core 3 on the opening portion of the case 4 side. The surface layer 5 has a resin portion formed of resin similar to the resin contained in the magnetic core 3. The resin portion is formed so as to be continuous with the resin contained in the magnetic core 3 without an interface formed therebetween.