metals therein for example it is possible for both the heat receiving jacket 2 and the heat radiation pipe 4 to be made of copper it often occurs that bacteria is mixed into the water which is used as the cooling liquid for example in the manufacturing process thereof even in such a case the structure having an area where the cooling liquid is in greatest contact with the copper can suppress the corrosion accompanying with the bacteria at the portion which is in contact with the cooling liquid thereby improving the reliability of the system as a whole also when the heat receiving jacket and the heat radiation pipe are made of the same kind of material the size and weight thereof can be made as small and light as possible thus such a technique is preferable when the system is to be applied to a personal computer that is of small size and is lightweight in that instance it is preferable to enclose or cover the member that is thinner in thickness with the waterproof sheet 8 in a case where the heat radiation pipe 4 and the heat receiving jacket 2 are made of copper and aluminum respectively it is possible to suppress the amount of corrosion by adding corrosion inhibiter agents for copper and aluminum into the coolant in advance as was fully explained in the above according to the present invention it is possible to provide a liquid cooling system that is suitable for cooling a high heat generation body such as a semiconductor device etc and to suppress ill influences following corrosion in the cooling system on the apparatus in which it is installed thereby ensuring the dependability of the system as a whole and a.