A heat generating body including a a moldable heat generating composition containing surplus water as a connecting substance interposed and heat sealed between packaging materials, which is characterized in that the packaging materials are each constituted of a substrate and a covering material that the substrate is substantially planar and does not have an accommodating pocket that the packaging materials each has a bending resistance of not more than 100 mm that the packaging materials are each a non-elastic body at least at a temperature between 25° C. and 60° C., has a breaking strength of 500 g/mm2 or more at 25° C. and has a breaking elongation of 30% or more at 90° C. The heat generating body is suitable for relaxation of symptoms of menstrual pain.
