A thin film deposition apparatus that can be simply applied to produce large-sized display devices on a mass scale and that improves manufacturing yield. The thin film deposition apparatus includes a deposition source that discharges a deposition material; a deposition source nozzle unit disposed at a side of the deposition source and including a plurality of deposition source nozzles arranged in a first direction; and a patterning slit sheet disposed opposite to the deposition source nozzle unit and including a plurality of patterning slits arranged in a second direction that is perpendicular to the first direction. A deposition is performed while the substrate or the thin film deposition apparatus moves relative to each other in the first direction, and the deposition source, the deposition source nozzle unit, and the patterning slit sheet are formed integrally with each other.