A liquid cooling system, enabling protection from corrosion due to liquid coolant for a long time-period (5 10 years) while cooling a heat-generation body effectively, comprises a pump 108, a heat-receiving jacket 107, a radiator for radiating heat into an outside, being made up with a heat-radiation pipe 201 and a heat-radiation plate 202, and further a tank 203 for accumulating the liquid coolant 209 within an inside thereof, wherein those are connected in a closed-loop, so as to circulating the cooling liquid therein, thereby cooling the heat-generation of a CPU 106, being a heat-generation element, effectively, through the heat-receiving jacket 107, and further a water-permeable bag 204 is disposed in a portion of flow path of the cooling liquid, which receives microcapsules 10 therein, each enclosing in an inside thereof anti-corrosion agent 20 for suppressing the corrosion due to the cooling liquid, including such as, a water, etc.