Provided is a heat insulation tool or a cold insulation tool which is capable of extending a heat insulation or cold insulation function by regenerating a latent heat storage material in the course of logistics and which is capable of assuredly retaining heat or keeping cool within a temperature range to be maintained for an object subjected to heat insulation or cold insulation by reducing variations in temperature during phase transition of the latent heat storage material. A heat insulation tool (100) is used for a packing container for logistics and is used for adjusting the temperature of an object subjected to heat insulation, the heat insulation tool being provided with: a latent heat storage material in which a difference between the solidification temperature and the melting initiation temperature is less than 1°C, the solidification temperature being the temperature at which phase transition from the liquid phase to the solid phase starts, the melting initiation temperature being the temperature at which phase transition from the solid phase to the liquid phase starts; and a housing part (120) which houses the latent heat storage material, wherein the latent heat storage material is selected according to the temperature range to be retained for the object subjected to heat insulation, so that the solidification temperature is within the temperature range to be retained for the object subjected to heat insulation, and the melting initiation temperature is lower than the upper limit of the temperature range to be retained for the object subjected to heat insulation.
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