An air conditioner comprising: a compressor for compressing a refrigerant; an outdoor heat-exchanger for exchanging heat with outdoor air; an indoor heat-exchanger for exchanging heat with indoor air; a converting valve for guiding the refrigerant discharged from the compressor to the outdoor heat-exchanger in a cooling operation and guiding the refrigerant to the indoor heat-exchanger in a heating operation; and an accumulator disposed between the compressor and the converting valve to separate the refrigerant into a liquid-phase refrigerant and a gas-phase refrigerant, characterized by further comprising: an accumulator jacket disposed on a surface of the accumulator and configured for containing a refrigerating fluid flowing therein to heat exchange with the accumulator to thereby be cooled; a supercooling heat-exchange hub configured for storing the refrigerating fluid cooled at the accumulator jacket and for overcooling the refrigerant flowing between the outdoor heat-exchanger and the indoor heat-exchanger; a circulating pump configured to forcibly circulate the refrigerating fluid flowing in the supercooling heat-exchange hub and the accumulator jacket; and a control unit configured, in the cooling operation, for controlling the converting valve to connect an outlet port of the compressor to the outdoor heat-exchanger and for driving the circulating pump, wherein the control unit is configured not to drive the circulating pump in the heating operation. a compressor for compressing a refrigerant; an outdoor heat-exchanger for exchanging heat with outdoor air; an indoor heat-exchanger for exchanging heat with indoor air; a converting valve for guiding the refrigerant discharged from the compressor to the outdoor heat-exchanger in a cooling operation and guiding the refrigerant to the indoor heat-exchanger in a heating operation; and an accumulator disposed between the compressor and the converting valve to separate the refrigerant into a liquid-phase refrigerant and a gas-phase refrigerant, characterized by further comprising: an accumulator jacket disposed on a surface of the accumulator and configured for containing a refrigerating fluid flowing therein to heat exchange with the accumulator to thereby be cooled; a supercooling heat-exchange hub configured for storing the refrigerating fluid cooled at the accumulator jacket and for overcooling the refrigerant flowing between the outdoor heat-exchanger and the indoor heat-exchanger; a circulating pump configured to forcibly circulate the refrigerating fluid flowing in the supercooling heat-exchange hub and the accumulator jacket; and a control unit configured, in the cooling operation, for controlling the converting valve to connect an outlet port of the compressor to the outdoor heat-exchanger and for driving the circulating pump, wherein the control unit is configured not to drive the circulating pump in the heating operation. an accumulator jacket disposed on a surface of the accumulator and configured for containing a refrigerating fluid flowing therein to heat exchange with the accumulator to thereby be cooled; a supercooling heat-exchange hub configured for storing the refrigerating fluid cooled at the accumulator jacket and for overcooling the refrigerant flowing between the outdoor heat-exchanger and the indoor heat-exchanger; a circulating pump configured to forcibly circulate the refrigerating fluid flowing in the supercooling heat-exchange hub and the accumulator jacket; and a control unit configured, in the cooling operation, for controlling the converting valve to connect an outlet port of the compressor to the outdoor heat-exchanger and for driving the circulating pump, wherein the control unit is configured not to drive the circulating pump in the heating operation.