An outdoor unit of an air conditioner is provided. The outdoor unit may include a compressor for compressing a refrigerant; a condenser for condensing the refrigerant discharged from the compressor; a control device for containing electronic parts to control the outdoor unit; and a cooling unit in contact with a heat generating part of the electronic parts to cool the heating unit, wherein the cooling unit comprises a first heat radiation member installed to be in contact with the heat generating part; a refrigerant pipe extending through the first heat radiation member and enabling a refrigerant to flow through the refrigerant pipe; and a second heat radiation member coupled with the first heat radiation member for heat transfer and installed to be in contact with outdoor air flowing into the control device.