PROBLEM TO BE SOLVED: To provide a gelatinous heat storage agent that is not liquefied when heated and moderately has shape retention； and to provide a heat insulation tool encapsulating the gelatinous heat storage agent.SOLUTION: The gelatinous heat storage agent includes, as a gelatinizer, at least one kind of heat-sensitive polymer that starts to gelatinize when having a temperature that is more than a certain temperature. In the gelatinizer, which is a heat-sensitive polymer having a viscosity of 5000 η or more at 40°C when left standing after heating, methyl cellulose is used. The ratio between water or a water-based composition and the gelatinizer is 99.8:0.2 to 90:10.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2018,JPO&INPIT【課題】加熱した際に液状化せず適度に保形性のあるゲル状蓄熱剤、およびそれを封入した保温具の提供。【解決手段】一定温度を超えるとゲル化を開始する少なくとも一種の感熱性高分子をゲル化剤として含有することを特徴とするゲル状蓄熱剤。ゲル化剤は加熱後の放冷時で４０℃における粘度が５０００η以上を有する感熱性高分子であり、メチルセルロースが用いられる。水または水系組成物とゲル化剤の割合は９９．８：０．２～９０：１０の割合である。【選択図】図１
