An organic layer deposition apparatus for forming an organic layer on a substrate includes: a deposition source configured to discharge a deposition material; a deposition source nozzle unit arranged at a side of the deposition source and including a plurality of deposition source nozzles; and a patterning slit sheet facing the deposition source nozzle unit and including a plurality of patterning slits and at least one spacer arranged between a pair of adjacent patterning slits of the plurality of patterning slits, the patterning slit sheet being smaller than the substrate in at least one of a first direction or a second direction perpendicular to the first direction, and the substrate is spaced apart from the organic layer deposition apparatus by a predetermined distance, and at least one of the substrate or the organic layer deposition apparatus is movable relative to the other.