An organic layer deposition assembly, an organic layer deposition apparatus, an organic light-emitting display apparatus, and a method of manufacturing the organic light-emitting display apparatus, in order to improve a characteristic of a deposited layer, the organic layer deposition assembly including a deposition source for discharging a deposition material; a deposition source nozzle unit disposed at a side of the deposition source, and including a plurality of deposition source nozzles; and a patterning slit sheet disposed while facing the deposition source nozzle unit, and including a plurality of patterning slits and one or more alignment confirmation pattern slits that are formed at edge portions of the plurality of patterning slits, wherein the deposition material that is discharged from the deposition source passes through the patterning slit sheet and then is formed on the substrate, while a deposition process is performed.