An organic light emitting display device is manufactured by: preparing a target substrate that includes sub-pixel areas (each having a thin film transistor) and pixel defining areas (each having a conductive layer) between the sub-pixel areas; preparing an ionized deposition material by vaporizing and ionizing a deposition material; applying a ground voltage to one of the sub-pixel areas while applying a voltage having a same polarity as the ionized deposition material to the neighboring ones of the sub-pixel areas and to the pixel defining areas; and depositing the ionized deposition material on the one of the sub-pixel areas to form an organic thin layer while the one of the sub-pixel areas is polarized by an electric field generated by the voltage being applied to the conductive layer of the pixel defining areas.