An organic light emitting display device includes a first transistor including a first active region and a first gate electrode disposed on the first active region, a third transistor including a third lower gate electrode disposed on the first gate electrode, a third active region disposed on the third lower gate electrode, and a third upper gate electrode disposed on the third active region, and a fourth transistor including a fourth active region disposed in the same layer as the first active region and a fourth gate electrode disposed on the fourth active region. The first transistor is a first-type transistor, and the fourth transistor is a second-type transistor different from the first-type transistor.