An electronic device includes an antenna, and a plate-shaped heat spreader including first and second metal layers that are stacked, a working fluid in an enclosed space interposed between the first and second metal layers, and a joint along which outer peripheral portions around the enclosed space are joined. The heat spreader includes an operational region in which the enclosed space is located and a quasi-operational region other than the enclosed space. The antenna is provided in the quasi-operational region in a plan view of the heat spreader.