An organic light emitting display device includes: a flexible substrate having a groove that is undercut; a common layer disposed on the flexible substrate, including an organic light emitting layer, and disconnected by the groove; and a sealing member disposed on the common layer and covering the common layer. The flexible substrate includes a first substrate layer and a first barrier layer disposed on the first substrate layer. The first barrier layer protrudes with respect to the first substrate layer at the groove. The first barrier layer that protrudes has a waveform.