Provided are an encapsulating structure, an organic light-emitting display device including the encapsulating structure, and a method of manufacturing the same. The encapsulating structure includes a first barrier layer including a first inorganic layer having a first thickness; a plasma polymer layer on the first inorganic layer, the plasma polymer layer having a second thickness smaller than or equal to the first thickness; and a second barrier layer including at least one second inorganic layer on the plasma polymer layer. The at least one second inorganic layer has a third thickness, and the third thickness is smaller than or equal to the second thickness.