Abstract: An apparatus for filling a heat storage material in a heat storage system for thermal energy delivery business is provided, wherein the heat storage system stores waste heat and is then moved a location where the heat is to be used, to dissipate the heat. According to the apparatus for filling a heat storage material, an accurate and uniform amount of a phase change material may be conveniently filled in the heat storage system while maintaining a liquid state of the heat storage material by melting the phase change material.