An air conditioner of an electric vehicle comprising: a compressor for compressing refrigerant; an indoor heat exchanger for performing heat exchange between refrigerant introduced into the indoor exchanger after emerging from the compressor and air; an outdoor heat exchanger for performing heat exchange between refrigerant introduced into the outdoor heat exchanger and outdoor air; a first expansion device arranged between the indoor heat exchanger and the outdoor heat exchanger, to expand refrigerant introduced into the first expansion device; an evaporator for evaporating refrigerant introduced into the evaporator, to dehumidify indoor air; a second expansion device arranged between the outdoor heat exchanger and the evaporator, to expand refrigerant introduced into the second expansion device; a first bypass line connected to guide refrigerant emerging from the indoor heat exchanger to flow toward the evaporator after bypassing the first expansion device and the outdoor heat exchanger, and a second bypass line connected to guide refrigerant flowing toward the evaporator to flow toward the compressor after bypassing the evaporator; an accumulator connected to the compressor, the accumulator receiving refrigerant; and a supercooler for performing heat exchange between refrigerant flowing between the evaporator and the outdoor heat exchanger and refrigerant flowing between the accumulator and the compressor; a first switch valve for performing a switching operation to allow refrigerant flowing toward the first expansion device to flow toward the first bypass line in a low-temperature heating mode; and a second switch valve for performing a switching operation to allow refrigerant flowing toward the evaporator to flow toward the second bypass line in a non-dehumidification mode, wherein, during a heating operation, the first bypass line is selectively used in accordance with an outdoor temperature, and the second bypass line is selectively used in accordance with an indoor humidity, wherein in the low-temperature heating mode, switching the first switch valve to allow refrigerant emerging from the indoor heat exchanger to flow toward the second switch valve without passing through the outdoor heat exchanger; switching the second switch valve to allow refrigerant emerging from the first switch valve to flow toward the evaporator; turning on the second expansion device, wherein the refrigerant emerging from the supercooler is expanded in the second expansion device, and is then supplied to the evaporator. a compressor for compressing refrigerant; an indoor heat exchanger for performing heat exchange between refrigerant introduced into the indoor exchanger after emerging from the compressor and air; an outdoor heat exchanger for performing heat exchange between refrigerant introduced into the outdoor heat exchanger and outdoor air; a first expansion device arranged between the indoor heat exchanger and the outdoor heat exchanger, to expand refrigerant introduced into the first expansion device; an evaporator for evaporating refrigerant introduced into the evaporator, to dehumidify indoor air; a second expansion device arranged between the outdoor heat exchanger and the evaporator, to expand refrigerant introduced into the second expansion device; a first bypass line connected to guide refrigerant emerging from the indoor heat exchanger to flow toward the evaporator after bypassing the first expansion device and the outdoor heat exchanger, and a second bypass line connected to guide refrigerant flowing toward the evaporator to flow toward the compressor after bypassing the evaporator; an accumulator connected to the compressor, the accumulator receiving refrigerant; and a supercooler for performing heat exchange between refrigerant flowing between the evaporator and the outdoor heat exchanger and refrigerant flowing between the accumulator and the compressor; a first switch valve for performing a switching operation to allow refrigerant flowing toward the first expansion device to flow toward the first bypass line in a low-temperature heating mode; and a second switch valve for performing a switching operation to allow refrigerant flowing toward the evaporator to flow toward the second bypass line in a non-dehumidification mode, wherein, during a heating operation, the first bypass line is selectively used in accordance with an outdoor temperature, and the second bypass line is selectively used in accordance with an indoor humidity, wherein in the low-temperature heating mode, switching the first switch valve to allow refrigerant emerging from the indoor heat exchanger to flow toward the second switch valve without passing through the outdoor heat exchanger; switching the second switch valve to allow refrigerant emerging from the first switch valve to flow toward the evaporator; turning on the second expansion device, wherein the refrigerant emerging from the supercooler is expanded in the second expansion device, and is then supplied to the evaporator.