An organic layer deposition apparatus includes: a conveyer unit including a transfer unit, a first conveyer unit, and a second conveyer unit; a loading unit for fixing a substrate to the transfer unit; a deposition unit including a chamber and at least one organic layer deposition assembly; and a measuring unit located between the loading unit and the deposition unit to measure position information of the substrate before an organic layer is deposited onto the substrate; and an unloading unit for separating, from the transfer unit, the substrate onto which the deposition has been completed, wherein the transfer unit is configured to cyclically move between the first conveyer unit and the second conveyer unit, and wherein the substrate fixed to the transfer unit is configured to be spaced apart from the at least one organic layer deposition assembly while being transferred by the first conveyer unit.