An object of the present invention is to provide a heat retaining device having a good touch and a high heat retaining effect. There are two types of heat insulation devices for covering a person's limbs with four bags 2； an upper limb bag 3 in which the upper limb fits and a lower limb bag 4 in which the lower limb fits, both of which absorb moisture. Sew and knit a knit fabric made by co-knitting exothermic fiber yarn and silk yarn. [Selection] Figure 1【課題】肌触りが良く且つ保温効果の高い保温具を提供する。【解決手段】人の四肢をそれぞれ４個の袋体２で被覆する保温具は、袋体２が上肢の収まる上肢袋３と、下肢の収まる下肢袋４との２種類があり、何れも吸湿発熱繊維糸と絹糸を交編したニット生地を縫製してループ状にして絡ませながら編み上げる。【選択図】図１
