A peripheral device is detachably connected to a host device and includes: an electronic component that generates heat; an electrical connector for electrically connecting the electronic component to the host device; a heat transfer device having a first end thermally connected to the electronic component; and a heat transfer connector thermally connecting a second of the heat transfer device to the host device. The heat generated by the electronic component is discharged, or transferred, to the host device side through the heat transfer device and the heat transfer connector.