There is provided such a heat-generating body for warming a foot in that a heat-generating composition is used that can retain the shape thereof irrespective of the pressure inside the container bag upon using by application to a foot, a footgear or a sock. The heat-generating body of the invention for warming a foot is characterized in that it contains a heat-generating formed article causing a heat-generating reaction in the presence of air and having a shape retaining degree of 70 or more charged in a container bag constituted with a base material, a covering material and the like. Further a process is provided for producing a heat-generating body for warming a foot in that the heat generation reaction of the heat-generating composition is suppressed to prevent loss due to the heat-generating reaction during production, quality deterioration of the heat-generating composition, and other problems.