To provide a cooling technology to sufficiently cool a server module mounted in a rack cabinet to secure the reliability thereof and to perform smooth heat dissipation of high heat generating components mounted on the server module especially, by using a liquid-cooling method without losing the advantages of a rack-mounted system even if the server module has improved performance, is made thin, and is high-density-packaged.

In a rack-mounted server system, the rack cabinet 10 is equipped with a cooling device 61 which is a heat exchanger that utilizes latent heat of a cooling medium, and an evaporator 43 which is a vaporization section for the rack cabinet is installed in the up and down direction along a pillar of the rack cabinet 10. In a plurality of liquid-cooled server modules 62, heat from heating sections 3 is transported to heat dissipation sections 25 installed outside the system by means of a cooling liquid circulated by pumps 23. By bringing the heat dissipation sections 25 into close contact with the evaporator 43, heat accumulated in the cooling liquid is absorbed by the cooling medium, and then the cooled cooling liquid is circulated to the heating sections 3 again.