A hot water circulation system comprising a heat pump, comprising: an outdoor unit including a compressor, an outdoor heat-exchanger, and an expansion part, and performing a heat pump refrigerant cycle; an indoor unit including a water-refrigerant heat-exchanger which performs heat exchange between a refrigerant discharged from the compressor and water, a water collection tank in which water passing through the water-refrigerant heat-exchanger is stored, and a water pump which pumps water discharged from the water collection tank; and a hot water circulation unit (4, 5) which receives heat from the water pumped by the water pump to perform hot water supply or heating, characterized in that the system includes: a by-pass valve provided at a discharge side of the compressor; a by-pass pipe extended from the bypass valve to be connected to an inlet side of the outdoor heat-exchanger; a pressure reduction device provided on the by-pass pipe to decompress refrigerant flowing in the bypass pipe; and an induction heater provided on an outer side of the outdoor heat-exchanger to supply defrosting heat to the outdoor heat exchanger; wherein the bypass valve is controlled such that a portion of a refrigerant discharged from the compressor is bypassed to the outdoor heat-exchanger when a temperature of the outdoor heat-exchanger is lower than a defrosting requisite temperature while hot water supply or heating is performed. an outdoor unit including a compressor, an outdoor heat-exchanger, and an expansion part, and performing a heat pump refrigerant cycle; an indoor unit including a water-refrigerant heat-exchanger which performs heat exchange between a refrigerant discharged from the compressor and water, a water collection tank in which water passing through the water-refrigerant heat-exchanger is stored, and a water pump which pumps water discharged from the water collection tank; and a hot water circulation unit (4, 5) which receives heat from the water pumped by the water pump to perform hot water supply or heating, characterized in that the system includes: a by-pass valve provided at a discharge side of the compressor; a by-pass pipe extended from the bypass valve to be connected to an inlet side of the outdoor heat-exchanger; a pressure reduction device provided on the by-pass pipe to decompress refrigerant flowing in the bypass pipe; and an induction heater provided on an outer side of the outdoor heat-exchanger to supply defrosting heat to the outdoor heat exchanger; wherein the bypass valve is controlled such that a portion of a refrigerant discharged from the compressor is bypassed to the outdoor heat-exchanger when a temperature of the outdoor heat-exchanger is lower than a defrosting requisite temperature while hot water supply or heating is performed. a by-pass valve provided at a discharge side of the compressor; a by-pass pipe extended from the bypass valve to be connected to an inlet side of the outdoor heat-exchanger; a pressure reduction device provided on the by-pass pipe to decompress refrigerant flowing in the bypass pipe; and an induction heater provided on an outer side of the outdoor heat-exchanger to supply defrosting heat to the outdoor heat exchanger; wherein the bypass valve is controlled such that a portion of a refrigerant discharged from the compressor is bypassed to the outdoor heat-exchanger when a temperature of the outdoor heat-exchanger is lower than a defrosting requisite temperature while hot water supply or heating is performed.