An organic layer deposition apparatus includes a conveyer unit and a deposition unit that has one or more organic layer deposition assemblies configured to deposit an organic layer on a moving substrate. The conveyer unit includes a moving unit configured to move a substrate fixed thereto, a first conveyer unit configured to move the moving unit in a first direction during which an organic material is deposited on the substrate fixed to the moving unit, and a second conveyer unit configured to move the moving unit in a second direction opposite to the first direction after deposition is completed and the substrate is separated from the moving unit. The first conveyer unit and the second conveyer unit are configured to move through the deposition unit.