Disclosed is a heat radiation device, which is in contact with a first heat-producing component having a higher value of guaranteed temperature and a second heat-producing component having a lower value of guaranteed temperature, and the heat radiation device comprises a metal member provided with a slit. The metal member is divided by the slit to have two heat radiation regions, a first heat radiation region and a second heat radiation region that are loosely coupled with each other in terms of heat conduction. The first heat-producing component is placed in contact with the first heat radiation region, and the second heat-producing component is placed in contact with the second heat radiation region.