An organic light emitting display device, comprising: a semi-transmissive electrode on a substrate; at least a first emission part, a second emission part, and a third emission part, wherein the first emission part is on the semi-transmissive electrode and includes a first hole transport layer, a first emission layer, and a first electron transport layer, wherein the second emission part is on the first emission part and includes a second hole transport layer, a second emission layer, and a second electron transport layer, wherein the third emission part is on the second emission part and includes a third hole transport layer, a third emission layer, and a third electron transport layer, wherein the first emission layer and the third emission layer each comprise one of a blue emission layer, a sky blue emission layer, and a deep blue emission layer, and the second emission layer comprises one of a yellow-green emission layer and a green emission layer, wherein a first charge generation layer is between the first emission part and the second emission part and a second charge generation layer is formed between the second emission part and the third emission part; and a reflective electrode on the third emission part, characterized in that at least one first organic layer is between the substrate and the first emission layer, the at least one first organic layer including at least the first hole transport layer and a sum of a thickness of the at least one first organic layer and a thickness of the semi-transmissive electrode is within a range from 165 nm to 240 nm such that a peak wavelength difference based on a viewing angle of each of the first emission layer and the third emission layer is 8 nm or less, and the peak wavelength difference based on the viewing angle of the second emission layer is 12 nm or less, wherein the peak wavelength difference is based on a viewing angle between 0 degrees and 60 degrees. a semi-transmissive electrode on a substrate; at least a first emission part, a second emission part, and a third emission part, wherein the first emission part is on the semi-transmissive electrode and includes a first hole transport layer, a first emission layer, and a first electron transport layer, wherein the second emission part is on the first emission part and includes a second hole transport layer, a second emission layer, and a second electron transport layer, wherein the third emission part is on the second emission part and includes a third hole transport layer, a third emission layer, and a third electron transport layer, wherein the first emission layer and the third emission layer each comprise one of a blue emission layer, a sky blue emission layer, and a deep blue emission layer, and the second emission layer comprises one of a yellow-green emission layer and a green emission layer, wherein a first charge generation layer is between the first emission part and the second emission part and a second charge generation layer is formed between the second emission part and the third emission part; and a reflective electrode on the third emission part, characterized in that at least one first organic layer is between the substrate and the first emission layer, the at least one first organic layer including at least the first hole transport layer and a sum of a thickness of the at least one first organic layer and a thickness of the semi-transmissive electrode is within a range from 165 nm to 240 nm such that a peak wavelength difference based on a viewing angle of each of the first emission layer and the third emission layer is 8 nm or less, and the peak wavelength difference based on the viewing angle of the second emission layer is 12 nm or less, wherein the peak wavelength difference is based on a viewing angle between 0 degrees and 60 degrees.