An air conditioner comprising: a heat exchanger that includes a plurality of heat transfer pipes, adapted to permit the flow of a refrigerant therethrough, and that is adapted to perform heat exchange with air, wherein the heat exchanger includes one end section and the other end section, the plurality of heat transfer pipes are disposed to extend back and forth between the one end section and the other end section in a state in which the heat transfer pipes are arranged in a direction crossing a direction in which the air flows, and rows of the plurality of heat transfer pipes arranged in the crossing direction are configured to be arranged in at least two rows along the direction in which the air flows; the two rows include a first row located most upstream in the direction in which the air flows and a second row located adjacent to the first row in the direction in which the air flows, the plurality of heat transfer pipes include a first heat transfer pipe and a second heat transfer- pipe adjacent to each other in the second row, the first heat transfer pipe and the second heat transfer pipe extend from the other end section to the one end section in the second row and are combined in the one end section to be a first combined pipe, and the first combined pipe is configured to extend back and forth once between the one end section and the other end section in the first row, the plurality of heat transfer pipes further include a third heat transfer pipe and a fourth heat transfer pipe adjacent to each other in the second row, the third heat transfer pipe and the forth heat transfer pipe are arranged to be adjacent to the first heat transfer pipe and the second heat transfer pipe and respectively extend from the other end section to the one end section in the second row, and are combined in the one end section to be a second combined pipe, and the second combined pipe is configured to extend back and forth between the one end section and the other end section in the first row, and a portion extending from the other end section to the one end section in the first combined pipe and a portion extending from the other end section to the one end section in the second combined pipe are arranged to be adjacent to each other. a heat exchanger that includes a plurality of heat transfer pipes, adapted to permit the flow of a refrigerant therethrough, and that is adapted to perform heat exchange with air, wherein the heat exchanger includes one end section and the other end section, the plurality of heat transfer pipes are disposed to extend back and forth between the one end section and the other end section in a state in which the heat transfer pipes are arranged in a direction crossing a direction in which the air flows, and rows of the plurality of heat transfer pipes arranged in the crossing direction are configured to be arranged in at least two rows along the direction in which the air flows; the two rows include a first row located most upstream in the direction in which the air flows and a second row located adjacent to the first row in the direction in which the air flows, the plurality of heat transfer pipes include a first heat transfer pipe and a second heat transfer- pipe adjacent to each other in the second row, the first heat transfer pipe and the second heat transfer pipe extend from the other end section to the one end section in the second row and are combined in the one end section to be a first combined pipe, and the first combined pipe is configured to extend back and forth once between the one end section and the other end section in the first row, the plurality of heat transfer pipes further include a third heat transfer pipe and a fourth heat transfer pipe adjacent to each other in the second row, the third heat transfer pipe and the forth heat transfer pipe are arranged to be adjacent to the first heat transfer pipe and the second heat transfer pipe and respectively extend from the other end section to the one end section in the second row, and are combined in the one end section to be a second combined pipe, and the second combined pipe is configured to extend back and forth between the one end section and the other end section in the first row, and a portion extending from the other end section to the one end section in the first combined pipe and a portion extending from the other end section to the one end section in the second combined pipe are arranged to be adjacent to each other.