Abstract: A disposable body warmer comprising a flat inner bag, heat-generating component which generates heat under presence of air being enclosed in the flat inner bag and an airtight bag enclosing the flat inner bag therein, characterized in that the heat-generating component contains potassium chloride, water, water-holding material, activated carbon and iron powder. With the disposable body warmer of the present invention, time required to reach a predetermined temperature from just after beginning of exothermic reaction is short, and duration in the predetermined temperature is long.

Abstract: A disposable body warmer in which a heat-generating agent which oxidizes and generates heat by the presence of air is contained in a flat bag. At least one surface of the flat bag is made air permeable so that pressure in the flat bag is reduced by exothermic reaction of the heat generating agent, and a self-adhesive layer is provided on either surface of the flat bag. Since the heat-generating agent contains high performance activated carbon having an iodine adsorption of 800 to 1200 mg/g and a methylene blue decoloring power of 100 to 300 mg/g, the rising in temperature is fast in comparison with conventional body warmers.