It relates to a heat-generating composition having such dispersion stability that withstands continuous molding, and has excellent drainage property, excellent heat-generating characteristics, excellent molding property and excellent shape retaining property, without becoming viscous, and relates to a heat-generating body using the same and a process for producing the heat-generating body. It contains, as essential components, a heat-generating substance generating heat upon reaction with oxygen, a carbon component, an oxidation promoter and water, characterized in that the composition further contains a water separation-preventing stabilizer in a proportion of from 0.001 to 0.25 part by mass per 100 parts by mass of the heat-generating composition, and has a water mobility value of from 7 to 40 and a separation degree of from 0 to 30.