An electronic cooling apparatus has a cabinet which is open at the front and rear sides thereof and accommodates plural electronic devices each having a fan, and a rear door which is provided with an evaporator. Air blown by the fan is cooled by the evaporator and then returned to a room. An expansion valve and control. A drain pan with an extension portion having hole portions through which refrigerant pipes extend is provided. A drain hose discharges drain water from the drain pan. An exhaust heat temperature detecting unit and a control for controlling the refrigerant supply to the evaporator are provided. When the exhaust heat temperature is equal to or less than a set exhaust temperature, the controller stops the refrigerant supply to the evaporator. When the exhaust heat temperature exceeds the set temperature, the controller starts the refrigerant supply.