PURPOSE: To enable a cooling bag to be rapidly and cryogenically cooled and keep its flexible characteristics and a soft touch feeling even if the bag is stored in a refrigerating freezer when the bag is reused by a method wherein an inner bag storing water therein is broken to cause the water to be absorbed into a carriage and then a main body of the cooling bag is cooled by an endothermic reaction of ammonium nitrate and urea immersed or adhered in the carriage and the water.

CONSTITUTION: A main body 1 is made such that a cooling body 4 having mixture 3 of aqueous urea and ammonium nitrate immersed or adhered to a plate-like carriage 2 made of urethane and non-woven fabric or the like and having a clearance therein and made of water absorption and flexible characteristics, and a flexible and high water-sealing outer enclosure 7 having an inner bag 6 of a thin film material filled with water 5 are sealingly closed and covered. As the main body 1 is pushed and crashed by hand during its use and the inner bag 6 is broken, the water 5 filled in the inner bag 6 is absorbed and held by the carriage 2, ammonium nitrate and urea are resolved in the water 5 to produce an endothermic reaction. Then, the endothermic reaction is remarkably promoted under a synergism between urea and ammonium nitrate and thus the main body 1 is rapidly cooled.