A method of manufacturing an organic light-emitting display apparatus includes: disposing an organic layer deposition apparatus to be apart from a substrate by a set distance; and depositing deposition material on the substrate while the organic layer deposition apparatus or the substrate is moved relative to the other, the deposition source apparatus including: a deposition source including a first deposition source and a second deposition source stacked on the first deposition source; a deposition source nozzle unit including a second deposition source nozzle unit at a side of the second deposition source to face the substrate and including a plurality of second deposition source nozzles, and a first deposition source nozzle unit at the side of the second deposition source to face the substrate and including a plurality of first deposition source nozzles formed to pass through the second deposition source; and a patterning slit sheet smaller than the substrate.