A heat pump includes an electric motor driven by input electric power, a first compressor mechanically connected to the electric motor and compresses air, a first heat exchanger performing heat exchange between compressed air produced by the first compressor and water, and a first hot water outlet through which the water heated by heat exchange in the first heat exchanger is taken out. Thus, in the air refrigerant heat pump, it is possible to use only air and water to supply heating by applying part of compressed air energy storage technology to the heat pump.