An organic light emitting display device, including: a substrate; a display unit formed on the substrate; and an encapsulation layer formed on the display unit, in which the encapsulation layer includes a lower layer formed on the display unit, at least one pattern layer formed on the lower layer, and an upper layer formed on the pattern layer, and the lower layer includes at least one of an inorganic film and an organic film, and the pattern layer includes an uneven pattern having a plurality of protrusions which are spaced apart from each other, formed on the lower layer, and a filling layer disposed on the uneven pattern, and the upper layer includes at least one of an inorganic film and an organic film.