An organic light emitting display device (100, 300) comprising: a first emission part (110, 310) including a first hole transport layer (112, 312), a first emission layer (114, 314), and a first electron transport layer (116, 316); a second emission part (120, 320) on the first emission part (110, 310), the second emission part (120, 320) including a second hole transport layer (122, 322), a second emission layer (124, 324), and a second electron transport layer (126, 326), wherein a thickness of the second hole transport layer (122, 322) is within a range of 5 nm to 10 nm; and a first charge generation layer provided between the first emission part (110, 310) and the second emission part (120, 320), wherein the first charge generation layer includes a first N-type charge generation layer and a first P-type charge generation layer (142, 342), wherein the second hole transport layer (122, 322) and the first P-type charge generation layer (142, 342) are disposed adjacent to each other, and wherein the first P-type charge generation layer (142, 242, 342) is formed of a material having hole-transporting properties and does not include a dopant, and the second hole transport layer (122, 322) comprises a mixture of a first material and a second material having different kinds of characteristics, wherein the first material and the second material are mixed by co-deposition, the hole mobility of the second material is within a range of approximately 1x10 -2 cm 2 /Vs to 1x10 -4 cm 2 /Vs, and an absolute value of a highest occupied molecular orbitals (HOMO) energy level of the first material being greater than an absolute value of a lowest unoccupied molecular orbitals (LUMO) energy level of the material of the first P-type charge generation layer (142, 342). a first emission part (110, 310) including a first hole transport layer (112, 312), a first emission layer (114, 314), and a first electron transport layer (116, 316); a second emission part (120, 320) on the first emission part (110, 310), the second emission part (120, 320) including a second hole transport layer (122, 322), a second emission layer (124, 324), and a second electron transport layer (126, 326), wherein a thickness of the second hole transport layer (122, 322) is within a range of 5 nm to 10 nm; and a first charge generation layer provided between the first emission part (110, 310) and the second emission part (120, 320), wherein the first charge generation layer includes a first N-type charge generation layer and a first P-type charge generation layer (142, 342), wherein the second hole transport layer (122, 322) and the first P-type charge generation layer (142, 342) are disposed adjacent to each other, and wherein the first P-type charge generation layer (142, 242, 342) is formed of a material having hole-transporting properties and does not include a dopant, and the second hole transport layer (122, 322) comprises a mixture of a first material and a second material having different kinds of characteristics, wherein the first material and the second material are mixed by co-deposition, the hole mobility of the second material is within a range of approximately 1x10 -2 cm 2 /Vs to 1x10 -4 cm 2 /Vs, and an absolute value of a highest occupied molecular orbitals (HOMO) energy level of the first material being greater than an absolute value of a lowest unoccupied molecular orbitals (LUMO) energy level of the material of the first P-type charge generation layer (142, 342).