Of electronic equipment cooling system

A while reducing losses due to evaporation of the cooling liquid, efficiently cool a plurality of electronic equipment located at a high density in a small volume of the cooling tank, to provide a cooling system. A cooling system 10, the coolant 13 inlet 14 and outlet 16 in the open space of the cooling bath 12 provided for, accommodating a plurality of electronic device 100, in the cooling fluid 13 flowing through the open space to, and is configured to direct cooling by immersing the plurality of electronic device 100. Coolant 13 comprises a fully fluorinated compound as the main component, usually 100 hours lapse of time obtained by spontaneous evaporation under environment of room temperature 25 ° C. Put liquid 10ml to 10ml graduated cylinder (opening diameter 11.5 mm) It is configured to liquid weight loss when it becomes 1.5% or less. The cooling liquid 13, vapor pressure at room temperature 25 ° C. of the coolant is equal to or less than 1.0 kPa, and / or the boiling point of the coolant can be configured to be at 0.99 ° C. or higher. .FIELD 1