A cooling system includes a first module, a second module provided at a different position in a depth direction of a housing with respect to the first module, a third module provided at a different position in a width direction of the housing with respect to the first module and the second module, an upstream side tube configured to supply a cooling medium to a cooling member of the first module, a downstream side tube configured to supply the cooling medium passed through the cooling member of the first module to a cooling member of the second module, and a branch tube configured to branch from the downstream side tube and supply the cooling medium to a cooling member of the third module.