Disclosed are an encapsulation unit which may prevent deterioration of thin film transistors so as to improve reliability and an organic light emitting display device including the same. At least one transparent oxide film is disposed under at least one of a plurality of inorganic encapsulation films disposed on a light emitting element and, thus, oxygen in the at least one transparent oxide film combines with hydrogen introduced during formation of the inorganic encapsulation films to prevent hydrogen from diffusing into the thin film transistors.