PURPOSE: To increase cold insulation time and improve a skin feeling touch by providing two inner bags, an outer covering layer outside an outer bag, and performing mixing operation between a hydrate agent and an endothermic agent contained in the inner bag and causing an endothermic reaction at least twice separately.

CONSTITUTION: A cold heat material pack 11 comprises a first inner bag 12A, a second inner bag 12B, an outer bag 15 which contains an endothermic agent 13, and an outer covering layer 14 which covers the their outside. The outer covering layer 14 forms a double structure which comprises an inner layer 14a containing a polymeric water absorption agent 18 and a non woven cloth 16b. A hydrate agent 16 is contained in the inner bags 12A and 12B. When a seal-breaking thread 17 is pulled out, the hydrate agent 16 in the inner bag 12A is discharged in the outer bag 15, and causes an endothermic reaction with an endothermic agent 13 contained in the outer bag 15, thereby lowering the temperature in the outer bag 15. As an inner layer 14a contains a polymeric hydrate agent 18, dew drops and human sweat outside the outer bag 15 are absorbed by the hydrate agent so that the outer covering layer may provide a cold and dry feeling touch to the skin to a satisfactory extent. Then, the inner bag 12B is opened in a similar manner so as to cause further endothermic reaction. As a result, the temperature in the outer bag 15 drops again. It is, therefore, possible to extend cold insulation time and provide a favorably dry feeling to the skin.