To provide a manufacturing method of a heating element which contains an oxidizable metal with a low bulk density, and is excellent in heat generating property.SOLUTION: A manufacturing method of a heating element 1 includes forming an application body 4 by applying onto a base material sheet 2, an exothermic composition 3 which contains an oxidizable metal having a bulk density of 0.3 g/cmor more and 1.5 g/cmor less, a carbon material and water, and has flowability, and removing water from the application body 4 so as to adjust a moisture content of the application body 4. It is preferable to remove water from the application body 4 so as to bring a moisture content contained in the application body 4 after removing water to equal to or less than a moisture content contained in the finally obtained heating element 1, and subsequently, to add water to the application body 4 so as to bring to a moisture content contained in the finally obtained heating element 1.SELECTED DRAWING: Figure 1【課題】かさ密度が低い被酸化性金属を含有し、発熱特性に優れた発熱体の製造方法を提供すること。【解決手段】本発明の発熱体１の製造方法は、かさ密度が０．３ｇ／ｃｍ３以上１．５ｇ／ｃｍ３以下である被酸化性金属、炭素材料及び水を含有し、且つ流動性を有する発熱組成物３を基材シート２上に塗布して塗布体４を形成し、塗布体４から水を除去して、塗布体４の水分量を調整する。水を除去した後の塗布体４に含まれる水分量が、最終的に得られる発熱体１に含まれる水分量以下となるように、塗布体４から水を除去し、次いで最終的に得られる発熱体１に含まれる水分量となるように、塗布体４に水を添加することが好ましい。【選択図】図１
