PURPOSE: To permit to supply hot-water through the hot-water reserving tank of small size by arranging the hot-water reserving tank so as to surround a compressor.

CONSTITUTION: The hot-water reserving tank 5 and a condenser 6, contacting with the tank 5, are arranged so as to surround the compressor 4. Heat exchange between water in the hot-water reserving tank 5 is effected in the condenser 6 and hot-water is supplied. In this case, all amount of heat, dissipated from the compressor 4, is given to the water in the tank 5, therefore, the efficiency of the device may be improved. In case the heat pump cycle of the device is re-started from the stopping condition thereof without using the hot- water to be supplied, heat is being given from the tank 5 to the compressor 4 during stopping the compressor 4 since the environment of the compressor 4 is insulated by a heat insulating member 7 surrounding the tank 5. Accordingly, the temperature of the compressor will never be reduced even during stopping the compressor 4.