This invention provides a heating tool that is capable of significantly suppressing a reduction of an active ingredient contained in an adhesive layer. More specifically, the invention provides a heating tool comprising an exothermic composition containing an oxidation accelerator, an oxidizable metal powder, and water an active ingredient-containing adhesive layer and a vapor deposition layer, the exothermic composition being housed in an air-permeable container bag, the vapor deposition layer being disposed between the container bag and the adhesive layer.
