A reactor 1 of the present invention includes: a combined product 10 provided with a coil 2 and a magnetic core 3 where the coil 2 is disposed; and a case 4 storing the combined product 10. The case 4 includes: a bottom plate portion 40 fixed to a fixation target when the reactor 1 is installed in the fixation target; a side wall portion 41 attached to the bottom plate portion 40 to surround the combined product 10; and a heat dissipation layer 42 formed on the inner face of the bottom plate portion 40 to be interposed between the bottom plate portion 40 and the coil 2. The bottom plate portion 40 is made of aluminum, and the side wall portion 41 is made of an insulating resin. The heat dissipation layer 42 is made of an adhesive agent whose thermal conductivity is high and which exhibits an excellent insulating characteristic. Since the bottom plate portion 40 is structured as a separate member from the side wall portion 41, the heat dissipation layer 42 can easily be formed and, moreover, the heat dissipation layer 42 can be made of a material possessing an excellent heat dissipating characteristic. Since the insulator 5 evenly presses the coil 2 against the heat dissipation layer 42, an even more excellent heat dissipating characteristic is achieved.