An organic light emitting display device including a flexible substrate and a plurality of thin film transistors (TFTs) formed on the substrate. The plurality of TFTs formed on the substrate include a pixel transistor for driving a pixel and a driver circuit transistor for driving a driver circuit, and a longitudinal direction of a channel region of the pixel transistor makes a first predetermined angle with a direction in which the substrate is bent. As such, it is possible to minimize a change in the electrical property of the TFTs formed on the flexible substrate and to thus reduce a change in the amount of current that flows in the channels of the TFTs.