In a cooling system for an electronic device of the present invention, server rooms in which a plurality of servers are placed, an evaporator which is provided close to each of the servers, and cools exhaust air from the server by vaporizing a refrigerant with heat generating from the server, a cooling tower which is provided at a place higher than the evaporator, cools the refrigerant by outside air and water sprinkling, and condenses the vaporized refrigerant, and a circulation line in which the refrigerant naturally circulates between the evaporator and the cooling tower. According to the cooling system, an electronic device which is required to perform a precise operation with a heat generation amount from itself being large, such as a computer and a server, can be efficiently cooled at low running cost.