There is provided a cold water tank including: a first tank having an inlet pipe through which water to be cooled is introduced; and a second tank provided in the interior of the first tank such that water of the first tank can be introduced thereinto, having an evaporator included in a refrigerating cycle to cool the introduced water, and having an outlet pipe through which cooled water flows. Although water is introduced at high pressure, the introduced water can remain in the cold water tank for a period of time required for being cooled, and although water is introduced at high pressure, the introduced water can be in a stable state in the cold water tank. Thus, water can be cooled with its inflow pressure maintained, and the degree of freedom of a faucet or cock for allowing cold water to flow therethrough can be improved in its height.