An air conditioner, comprising: a compressor configured to compress refrigerant; a condenser configured to perform exchange heat with refrigerant received from the compressor; an expansion device configured to decompress refrigerant passing through the condenser; an evaporator configured to perform heat exchange with refrigerant decompressed by the expansion device, wherein at least one of the condenser or the evaporator comprises: at least one heat exchange tube formed of an aluminum material and configured to guide refrigerant therethrough; and at least one fin coupled to the at least one heat exchange tube, the at least one fin being formed of the same material as that of the heat exchange tube; and a plurality of refrigerant tubes connecting the compressor, the condenser, the expansion device and the evaporator to guide refrigerant therebetween, wherein at least one of the plurality of refrigerant tubes comprising a combination tube in which an aluminum tube and a copper tube are coupled and the aluminum tube and the copper tube are aligned end to end with a space formed between corresponding ends; characterised by a coupling tube that couples the aluminum tube and the copper tube and into which the aluminum tube and the copper tube are inserted, the coupling tube comprising a first metal tube formed of the same material as that of the aluminum tube, and a second metal tube formed of the same material as that of the copper tube; a seal that surrounds the first and second metal tubes; and an adhesive layer provided between the first and second metal tubes and the seal, wherein the first metal tube surrounds the aluminum tube and does not directly contact the copper tube, and the second metal tube surrounds the copper tube and does not directly contact the aluminum tube. a compressor configured to compress refrigerant; a condenser configured to perform exchange heat with refrigerant received from the compressor; an expansion device configured to decompress refrigerant passing through the condenser; an evaporator configured to perform heat exchange with refrigerant decompressed by the expansion device, wherein at least one of the condenser or the evaporator comprises: at least one heat exchange tube formed of an aluminum material and configured to guide refrigerant therethrough; and at least one fin coupled to the at least one heat exchange tube, the at least one fin being formed of the same material as that of the heat exchange tube; and a plurality of refrigerant tubes connecting the compressor, the condenser, the expansion device and the evaporator to guide refrigerant therebetween, wherein at least one of the plurality of refrigerant tubes comprising a combination tube in which an aluminum tube and a copper tube are coupled and the aluminum tube and the copper tube are aligned end to end with a space formed between corresponding ends; at least one heat exchange tube formed of an aluminum material and configured to guide refrigerant therethrough; and at least one fin coupled to the at least one heat exchange tube, the at least one fin being formed of the same material as that of the heat exchange tube; and a plurality of refrigerant tubes connecting the compressor, the condenser, the expansion device and the evaporator to guide refrigerant therebetween, wherein at least one of the plurality of refrigerant tubes comprising a combination tube in which an aluminum tube and a copper tube are coupled and the aluminum tube and the copper tube are aligned end to end with a space formed between corresponding ends; characterised by a coupling tube that couples the aluminum tube and the copper tube and into which the aluminum tube and the copper tube are inserted, the coupling tube comprising a first metal tube formed of the same material as that of the aluminum tube, and a second metal tube formed of the same material as that of the copper tube; a seal that surrounds the first and second metal tubes; and an adhesive layer provided between the first and second metal tubes and the seal, wherein the first metal tube surrounds the aluminum tube and does not directly contact the copper tube, and the second metal tube surrounds the copper tube and does not directly contact the aluminum tube.