An air conditioner, comprising: a compressor that compresses a refrigerant; a condenser (21, 41) that condenses the refrigerant compressed in the compressor; an expander that expands the refrigerant condensed in the condenser (21, 41); an evaporator (41, 21) that evaporates the refrigerant expanded in the expander; a bypass pipe that bypasses the refrigerant discharged from the condenser (21, 41) to an inlet side of the compressor; a refrigerant heating apparatus that heats the refrigerant flowing in the bypass pipe; and a valve that controls the refrigerant flowing in the bypass pipe, characterized in that the refrigerant heating apparatus includes: a refrigerant pipe in which the refrigerant flows; and a heating unit that is provided on an outer surface of the refrigerant pipe, the heating unit including: a carbon nanotube heating element that generates heat with a supplied power; an insulating sheet that is formed on the outer surface of the refrigerant pipe; and a pair of electrodes (122, 123) that is formed on the upper surface of the insulating sheet and is spaced from each other, and wherein one end of the carbon nanotube heating element is electrically connected to any one of the pair of electrodes (122, 123) and the other is electrically connected to the other electrode (123, 122). a compressor that compresses a refrigerant; a condenser (21, 41) that condenses the refrigerant compressed in the compressor; an expander that expands the refrigerant condensed in the condenser (21, 41); an evaporator (41, 21) that evaporates the refrigerant expanded in the expander; a bypass pipe that bypasses the refrigerant discharged from the condenser (21, 41) to an inlet side of the compressor; a refrigerant heating apparatus that heats the refrigerant flowing in the bypass pipe; and a valve that controls the refrigerant flowing in the bypass pipe, characterized in that the refrigerant heating apparatus includes: a refrigerant pipe in which the refrigerant flows; and a heating unit that is provided on an outer surface of the refrigerant pipe, the heating unit including: a carbon nanotube heating element that generates heat with a supplied power; an insulating sheet that is formed on the outer surface of the refrigerant pipe; and a pair of electrodes (122, 123) that is formed on the upper surface of the insulating sheet and is spaced from each other, and wherein one end of the carbon nanotube heating element is electrically connected to any one of the pair of electrodes (122, 123) and the other is electrically connected to the other electrode (123, 122). a refrigerant pipe in which the refrigerant flows; and a heating unit that is provided on an outer surface of the refrigerant pipe, the heating unit including: a carbon nanotube heating element that generates heat with a supplied power; an insulating sheet that is formed on the outer surface of the refrigerant pipe; and a pair of electrodes (122, 123) that is formed on the upper surface of the insulating sheet and is spaced from each other, and wherein one end of the carbon nanotube heating element is electrically connected to any one of the pair of electrodes (122, 123) and the other is electrically connected to the other electrode (123, 122). a carbon nanotube heating element that generates heat with a supplied power; an insulating sheet that is formed on the outer surface of the refrigerant pipe; and a pair of electrodes (122, 123) that is formed on the upper surface of the insulating sheet and is spaced from each other, and wherein one end of the carbon nanotube heating element is electrically connected to any one of the pair of electrodes (122, 123) and the other is electrically connected to the other electrode (123, 122).