The present disclosure relates to a polybenzimidazole-based electrolyte membrane for alkaline water electrolysis, which includes a polybenzimidazole-based polymer, wherein the polybenzimidazole-based polymer is a biaxially oriented film. The polybenzimidazole-based electrolyte membrane for alkaline water electrolysis can reduce the concentration of an alkaline solution by improving the crystallinity of a polybenzimidazole-based polymer to increase the resistance against base, significantly improving the long-term stability of alkaline water electrolysis using a polybenzimidazole-based electrolyte membrane through the improved resistance against base, and by increasing the operation temperature to enhance the catalyst activity.