A heat exchanger comprising: a first-row heat exchange module through which a refrigerant is introduced from the outside; a second-row heat exchange module through which the refrigerant is discharged to the outside; a third-row heat exchange module through which the refrigerant is discharged to the outside, the first-row heat exchange module, the second-row heat exchange module, and the third-row heat exchange module are stacked in a ventilation direction; and a flow-splitting module that splits the refrigerant introduced from the first-row heat exchange module into the second-row heat exchange module and the third-row heat exchange module, wherein the refrigerant reciprocates one time in a flow path between an inlet, through which the refrigerant is introduced, and an outlet, through which the refrigerant is discharged, the first-row heat exchange module constitutes a forward path of the flow path, and both the second-row heat exchange module and the third-row heat exchange module constitute a backward path (50bU, 50cU) of the flow path, characterized in that the flow-splitting module splits the refrigerant such that an amount of the refrigerant flowing into the second-row heat exchange module arranged on a windward side in the ventilation direction is larger than an amount of the refrigerant flowing into the third-row heat exchange module on a leeward side arranged in the ventilation direction of the second-row heat exchange module and the flow-splitting module includes a first flow-splitting chamber, a second flow-splitting chamber, and a third flow-splitting chamber that communicate with the first-row heat exchange module, the second-row heat exchange module, and the third-row heat exchange module, respectively, and a diameter of a first inflow port connecting the first flow-splitting chamber and the second flow-splitting chamber to each other is larger than a diameter of a second inflow port connecting the first flow-splitting chamber and the third flow-splitting chamber to each other. a first-row heat exchange module through which a refrigerant is introduced from the outside; a second-row heat exchange module through which the refrigerant is discharged to the outside; a third-row heat exchange module through which the refrigerant is discharged to the outside, the first-row heat exchange module, the second-row heat exchange module, and the third-row heat exchange module are stacked in a ventilation direction; and a flow-splitting module that splits the refrigerant introduced from the first-row heat exchange module into the second-row heat exchange module and the third-row heat exchange module, wherein the refrigerant reciprocates one time in a flow path between an inlet, through which the refrigerant is introduced, and an outlet, through which the refrigerant is discharged, the first-row heat exchange module constitutes a forward path of the flow path, and both the second-row heat exchange module and the third-row heat exchange module constitute a backward path (50bU, 50cU) of the flow path, characterized in that the flow-splitting module splits the refrigerant such that an amount of the refrigerant flowing into the second-row heat exchange module arranged on a windward side in the ventilation direction is larger than an amount of the refrigerant flowing into the third-row heat exchange module on a leeward side arranged in the ventilation direction of the second-row heat exchange module and the flow-splitting module includes a first flow-splitting chamber, a second flow-splitting chamber, and a third flow-splitting chamber that communicate with the first-row heat exchange module, the second-row heat exchange module, and the third-row heat exchange module, respectively, and a diameter of a first inflow port connecting the first flow-splitting chamber and the second flow-splitting chamber to each other is larger than a diameter of a second inflow port connecting the first flow-splitting chamber and the third flow-splitting chamber to each other.