Abstract: A cooling water circulation apparatus is capable of limiting attachment of microorganisms and scale in an environmentally friendly manner. An electrolytic device 10 is provided on a cooling water circulation route R1. In the arrangement, mineral contents such as calcium ions and magnesium ions contained in cooling water W are deposited as scale S on an electrode 12A or 12B in an electrolytic step, thereby enabling the mineral contents to be removed from the cooling water W. Even if the hardness of the cooling water W is increased by evaporation of the water with elapse of time, the hardness can be reduced by the electrolytic processing. Thus, the deposition of the scale S in the circulation route R1 can be reduced. Further, the scale S deposited on the electrode 12A or 12B can be easily separated by operating while reversing the polarities of the electrodes 12A and 12B at predetermined time intervals.