To efficiently cool down heat of a heating element 20, this electronic device 100 is provided with a circuit board 10 having a heating element 20 that is attached to a first main surface 11 thereof, a case 30 having an opening part 31 that is formed in a surface facing the heating element 20 and housing a refrigerant COO therein, and a connection part 40 connecting the opening part 31 and the heating element 20 so as to enclose the refrigerant COO, the connecting part has a thickness of at most 0.21 mm.