A water circulation and refrigerant cycle system, comprising: an outdoor unit comprising a compressor (120, 120') for compressing the refrigerant, an outdoor heat exchanger for heat exchange between the refrigerant and outdoor air, and an expansion unit (102, 204, 152) for expanding the refrigerant; a water-heat exchange indoor unit comprising a water-refrigerant heat exchanger for heat exchange between the refrigerant and water, the water-refrigerant heat exchanger being connected to the compressor and the expansion unit; a hot water supply unit to supply the water passing through the water-refrigerant heat exchanger; a heating unit for heating the indoor air using the water passing through the water-refrigerant heat exchanger; and a heating apparatus that is connected to the outdoor unit to heat the refrigerant, characterized in that the heating apparatus comprises: a working fluid-refrigerant heat exchanger for heat exchange between the refrigerant and a working fluid, wherein the working fluid is water; a working fluid heating unit for heating the working fluid passing through the working fluid-refrigerant heat exchanger; a pump for allowing the heated working fluid to forcedly flow; and a heating tank for storing the heated working fluid; a plurality of circulation pipes (712, 714, 715) communicating with the outdoor unit to allow the refrigerant to circulate inside of the heating apparatus, the plurality of circulation pipes including a first circulation pipe, a second circulation pipe configured to merge with the first circulation pipe and a third circulation pipe communicating with the first circulation pipe; and an overheating prevention pipe provided at a side of the first circulation pipe and configured to communicate the first circulation pipe with the third circulation pipe to allow a part of the refrigerant introduced through the first circulation pipe to flow into the third circulation pipe. an outdoor unit comprising a compressor (120, 120') for compressing the refrigerant, an outdoor heat exchanger for heat exchange between the refrigerant and outdoor air, and an expansion unit (102, 204, 152) for expanding the refrigerant; a water-heat exchange indoor unit comprising a water-refrigerant heat exchanger for heat exchange between the refrigerant and water, the water-refrigerant heat exchanger being connected to the compressor and the expansion unit; a hot water supply unit to supply the water passing through the water-refrigerant heat exchanger; a heating unit for heating the indoor air using the water passing through the water-refrigerant heat exchanger; and a heating apparatus that is connected to the outdoor unit to heat the refrigerant, characterized in that the heating apparatus comprises: a working fluid-refrigerant heat exchanger for heat exchange between the refrigerant and a working fluid, wherein the working fluid is water; a working fluid heating unit for heating the working fluid passing through the working fluid-refrigerant heat exchanger; a pump for allowing the heated working fluid to forcedly flow; and a heating tank for storing the heated working fluid; a working fluid-refrigerant heat exchanger for heat exchange between the refrigerant and a working fluid, wherein the working fluid is water; a working fluid heating unit for heating the working fluid passing through the working fluid-refrigerant heat exchanger; a pump for allowing the heated working fluid to forcedly flow; and a heating tank for storing the heated working fluid; a plurality of circulation pipes (712, 714, 715) communicating with the outdoor unit to allow the refrigerant to circulate inside of the heating apparatus, the plurality of circulation pipes including a first circulation pipe, a second circulation pipe configured to merge with the first circulation pipe and a third circulation pipe communicating with the first circulation pipe; and an overheating prevention pipe provided at a side of the first circulation pipe and configured to communicate the first circulation pipe with the third circulation pipe to allow a part of the refrigerant introduced through the first circulation pipe to flow into the third circulation pipe.