A cooling device for heat-generating devices that are removably inserted into a plurality of slots formed in a cabinet of an electronic apparatus, the cooling device includes: a first cooling device provided in the electronic apparatus; a second cooling device provided outside the electronic apparatus; and a flexible tube that interconnects the first cooling device and the second cooling device so that a coolant is circulated; wherein the first cooling device includes a coolant flow path that is connected to one end of the flexible tube, the coolant flow path cooling both side surfaces of each of the plurality of slots, wherein the second cooling device includes a connector connected to another end of the flexible tube, a cooling unit that cools the coolant, which enters the second cooling device through the flexible tube, and a pump that feeds out the coolant, which has been cooled, to the flexible tube.