The present invention provides an excellent heating tool in which the generation of unpleasant odors is suppressed. The present invention also provides an excellent heating tool in which changes in aroma are suppressed. The present invention further provides an excellent heating tool in which the generation of unpleasant odors and changes in aroma are suppressed even after storage. The present invention provides a method for suppressing the generation of unpleasant odors and changes in aroma in a heating tool. The present invention provides a heating tool comprising an exothermic composition containing a metal ion sequestrant, an oxidizable metal powder, a water-soluble salt, and water, wherein at least the exothermic composition is housed in an air-permeable container bag.