The present invention relates to an organic light emitting device and a method of preparing the same. More particularly, the organic light emitting device according to the present invention includes: a substrate; an organic light emitting unit in which a first electrode, an organic material layer, and a second electrode are sequentially stacked on the substrate; and an encapsulating unit configured to seal an external side of the organic light emitting unit, in which a protecting unit is provided on at least a partial region of the substrate, on which the organic light emitting unit and the encapsulating unit are not provided, and at least a partial region in a lateral surface region of the substrate.