PURPOSE: To provide a barley water cooler operated under a stable condition for a long period of time and showing a high cooling efficiency in a less expensive manner by a method wherein the barley water containing adhesive substance therein in a heat exchanger using a Peltier element and in a thermos bottle is circulated and cooled by pneumatic pressure.

CONSTITUTION: Barley water W is filled in a thermos bottle 3 with a proper upper spacing being left on the barley water. The upper spacing is pressurized by a pressurized air generated when a bellows pump is retracted. The barley water W is injected from an injection nozzle 9 at an extremity end of a water feeding pipe 8 opened at a bottom part of the thermos bottle 3 and then the barley water W strikes against an inner wall 22 of a heat exchanger heat absorbed and freezed by a Peltier element 10. The barly water W is expanded in a radial form along the inner wall 22, its heat is absorbed while the water runs along the inner wall 22, drops into a water receptacle 7 and accumulated there. Then, the upper spacing in the thermos bottle 3 is reduced in its pressure by a reduced pressure produced when the bellows pump is expanded, a valve 16 at a water absorption hole 15 is opened, the barley water W accumulated at the water receptacle 7 is sucked back from the water absorption hole 15 into the thermos bottle 3, the water is settled at the bottom part of the thermos bottle 3 and convected there. The barley water W at the bottom part of the thermos bottle 3 is injected and struck against the inner wall 22 of the heat exchanger during a retracting period of the bellows. This operation is repeated and the barley water W in the thermos bottle 3 is circulated and cooled.