The invention relates to an outdoor unit of an air conditioner, incorporating a compressor, a heat exchanger, and a blower in a housing, wherein in an upper part of the one side face of the housing, an opening is provided, in a lower part of the one side face of the housing, a piping connection section is arranged to which refrigerant piping is connected, a recess provided, to serve as a handle, in a cover covering the piping connection section is inserted in the opening, and an upper wall of the opening makes contact with an outer wall of the recess.