An organic light emitting display device comprising a plurality of pixels (P1,P2), each of the plurality of pixels (P1,P2) comprising: a first sub-pixel including a first emission region which emits a first color light; a second sub-pixel disposed adjacent to the first sub-pixel , and including a second emission region which emits a second color light; a third sub-pixel disposed adjacent to the first sub-pixel , and including a third emission region which emits the second color light; and a fourth sub-pixel disposed adjacent to the second and third sub-pixels , and including a fourth emission region which emits a third color light, wherein the first, second and third colors are different from another; and at least one of the first, second, third or fourth sub-pixels comprising a transmission region which cannot emit light and through which external light is transmitted, wherein: the second sub-pixel is aligned adjacent to the first sub-pixel in a first direction (H), the third sub-pixel is aligned adjacent to the first sub-pixel in a second, perpendicular direction (V), and the fourth sub-pixel is aligned adjacent to the third sub-pixel in the first direction (H) and is adjacent to the second sub-pixel in the second direction (V), and wherein: the transmission region includes a first transmission region which is disposed in the first sub-pixel , a second transmission region which is disposed in the second sub-pixel , and a third transmission region which is disposed in the third sub-pixel , wherein the fourth sub-pixel does not include the transmission region and the fourth emission region of the fourth sub-pixel is an emission region of which emission efficiency is the lowest among the first to fourth emission regions . a first sub-pixel including a first emission region which emits a first color light; a second sub-pixel disposed adjacent to the first sub-pixel , and including a second emission region which emits a second color light; a third sub-pixel disposed adjacent to the first sub-pixel , and including a third emission region which emits the second color light; and a fourth sub-pixel disposed adjacent to the second and third sub-pixels , and including a fourth emission region which emits a third color light, wherein the first, second and third colors are different from another; and at least one of the first, second, third or fourth sub-pixels comprising a transmission region which cannot emit light and through which external light is transmitted, the second sub-pixel is aligned adjacent to the first sub-pixel in a first direction (H), the third sub-pixel is aligned adjacent to the first sub-pixel in a second, perpendicular direction (V), and the fourth sub-pixel is aligned adjacent to the third sub-pixel in the first direction (H) and is adjacent to the second sub-pixel in the second direction (V), and wherein: the transmission region includes a first transmission region which is disposed in the first sub-pixel , a second transmission region which is disposed in the second sub-pixel , and a third transmission region which is disposed in the third sub-pixel , wherein the fourth sub-pixel does not include the transmission region and the fourth emission region of the fourth sub-pixel is an emission region of which emission efficiency is the lowest among the first to fourth emission regions . <EOS>