An outdoor heat exchanger configured to be included in an air conditioner and configured to operate as a condenser in a cooling operation of the air conditioner and as an evaporator in a heating operation of the air conditioner, the outdoor heat exchanger comprising: a plurality of plates; a plurality of first refrigerant tubes penetrating the plurality of plates and aligned in a single row; a plurality of second refrigerant tubes penetrating the plurality of plates and aligned in a single row while being spaced apart from the plurality of first refrigerant tubes; a plurality of third refrigerant tubes penetrating the plurality of plates and aligned in a single row while being spaced apart from the plurality of first refrigerant tubes, a plurality of first return bands connecting the plurality of first refrigerant tubes and the plurality of second refrigerant tubes; a plurality of second return bands connecting the plurality of first refrigerant tubes and the plurality of third refrigerant tubes; a distribution module connected to the plurality of third refrigerant tubes; a condensation header pipe connected to the plurality of second refrigerant tubes and a liquid line; an evaporation header pipe connected to the plurality of first return bands and the liquid line; a check valve disposed between the condensation header pipe and the liquid line; and an outdoor expansion valve disposed between the evaporation header pipe and the liquid line, wherein the distribution module is directly connected to the plurality of third refrigerant tubes and is configured to supply a refrigerant to the plurality of third refrigerant tubes in the cooling operation, wherein a refrigerant, supplied from the distribution module and passing through the plurality of third refrigerant tubes, the plurality of second return bands, the plurality of first refrigerant tubes, the plurality of first return bands, and the plurality of second refrigerant tubes, flows into the condensation header pipe in the cooling operation, wherein the evaporation header pipe is directly connected to the plurality of first return bands and is configured to supply a refrigerant to the plurality of first return bands in the heating operation, wherein a refrigerant, supplied from the evaporation header pipe and passing through the plurality of first return bands, the plurality of first refrigerant tubes, the plurality of second return bands, and the plurality of third refrigerant tubes, flows into the distribution module in the heating operation, and wherein, with respect to a flow direction of outdoor air, the plurality of second refrigerant tubes is configured to be disposed in a front of the plurality of first refrigerant tubes while the plurality of third refrigerant tubes is configured to be disposed in a rear of the plurality of first refrigerant tubes. a plurality of plates; a plurality of first refrigerant tubes penetrating the plurality of plates and aligned in a single row; a plurality of second refrigerant tubes penetrating the plurality of plates and aligned in a single row while being spaced apart from the plurality of first refrigerant tubes; a plurality of third refrigerant tubes penetrating the plurality of plates and aligned in a single row while being spaced apart from the plurality of first refrigerant tubes, a plurality of first return bands connecting the plurality of first refrigerant tubes and the plurality of second refrigerant tubes; a plurality of second return bands connecting the plurality of first refrigerant tubes and the plurality of third refrigerant tubes; a distribution module connected to the plurality of third refrigerant tubes; a condensation header pipe connected to the plurality of second refrigerant tubes and a liquid line; an evaporation header pipe connected to the plurality of first return bands and the liquid line; a check valve disposed between the condensation header pipe and the liquid line; and an outdoor expansion valve disposed between the evaporation header pipe and the liquid line, wherein the distribution module is directly connected to the plurality of third refrigerant tubes and is configured to supply a refrigerant to the plurality of third refrigerant tubes in the cooling operation, wherein a refrigerant, supplied from the distribution module and passing through the plurality of third refrigerant tubes, the plurality of second return bands, the plurality of first refrigerant tubes, the plurality of first return bands, and the plurality of second refrigerant tubes, flows into the condensation header pipe in the cooling operation, wherein the evaporation header pipe is directly connected to the plurality of first return bands and is configured to supply a refrigerant to the plurality of first return bands in the heating operation, wherein a refrigerant, supplied from the evaporation header pipe and passing through the plurality of first return bands, the plurality of first refrigerant tubes, the plurality of second return bands, and the plurality of third refrigerant tubes, flows into the distribution module in the heating operation, and wherein, with respect to a flow direction of outdoor air, the plurality of second refrigerant tubes is configured to be disposed in a front of the plurality of first refrigerant tubes while the plurality of third refrigerant tubes is configured to be disposed in a rear of the plurality of first refrigerant tubes.