PURPOSE: To set a sheet in water to cause the water to be reacted with a heat absorbing agent, realize a rapid cooling function and after the consuming of heat absorbing agent, to realize the gradual cooling performance of a long period of time by a method wherein some water absorbing resin and heat absorbing agent absorbing heat when disolved in the water are enclosed in a sheet of which at least one surface can pass water therethrough and having a flexible characteristic.

CONSTITUTION: Water transparent sheets S1 and S2 are adhered in a specified spacing to form some bag-like spacings 1a between the grooves 1b and 1b. Particulate nitric acid ammonium as well as water absorbing resin 2 are enclosed the bag-like spacings 1a. As the cooling sheet 1 is immersed in water, the water enters from the water transparent sheet S2 into the interior part thereof and the water is absorbed in the water absorbing resin 2. Nitric acid ammonium is melted through water absorption, a surrounding heat is absorbed, and it is rapidly cooled. The sheet is immersed in water and wound around a struck affected part, thereby the affected part is rapidly cooled to enable an emergency treatment to be carried out. At the stage where a solution of nitric acid ammonium is ended, the water in the water absorbing resin 2 is cooled by nitric acid ammonium and cold heat is accumulated, so that the cool air is gradually evaporated and then the affected part is cooled well for a long period of time.