To provide a chemical heat pump having excellent durability in repeating a heat cycle at high temperature and capable of efficiently utilizing high-temperature waste heat over 1,000C.

The heat pump comprises a high-temperature side reactor filled with high-temperature side carbon dioxide gas absorption material composed mostly of multiple oxide expressed in general formula of Ba2TiO4, a low-temperature side reactor filled with low-temperature side carbon dioxide gas absorption material composed mostly of CaO, and a carbon dioxide flow passage for moving carbon dioxide gas between the high-temperature side reactor and the low-temperature side reactor. The pump utilizes (a) endoergic reaction when the high-temperature side carbon dioxide gas absorption material emits the carbon dioxide gas, (b) exoergic reaction when the carbon dioxide gas emitted from the high-temperature side carbon dioxide gas absorption material is absorbed by the low-temperature side carbon dioxide gas absorption material, (c) endoergic reaction when the low-temperature side carbon dioxide gas absorption material emits the carbon dioxide gas, and (d) exoergic reaction when the carbon dioxide gas emitted from the low-temperature side carbon dioxide gas absorption material is absorbed by the high-temperature side carbon dioxide gas absorption material.