A water purifier for stably supplying cold water and cold functional water through a single cooling system and a control method thereof are disclosed. The water purifier includes: a water flow line allowing purified water to move therethrough； a gas storage unit storing gas； a gas flow line (or a gas movement line) allowing the gas to flow from the gas storage unit； an ice storage tank heat-exchanging purified water provided through the water flow line with iced water to allow cold water to be discharged； and a mixture tank allowing the cold water which has been cooled in the ice storage tank to be mixed with the gas received through the gas flow line.
