Disclosed is a deposition apparatus for an organic light-emitting diode, which is capable of preventing a large piece of glass from sagging due to gravity. The deposition apparatus allows the glass to be adhered to the lower surface of a planar electrostatic chuck from the center portion toward the edge portion thereof in the state in which it is upwardly convexly bent, thereby preventing deformation of a mask caused by the amount of sag of the glass. In addition, the deposition apparatus enables rapid alignment of the glass and the mask because the glass and the mask are adhered to each other via measurement of respective alignment marks provided thereon after the glass is located as close as possible to the mask without coming into contact with the mask.