A gas barrier substrate including a first gas barrier layer, a substrate, and a second gas barrier layer is provided. The first gas barrier layer has a central bonding surface bonded with the substrate and a peripheral boding surface surrounding the central bonding surface. The second gas barrier layer entirely covers the substrate and the first gas barrier layer. The second gas barrier layer is bonded with the substrate and the peripheral boding surface of the first gas barrier layer, wherein a minimum distance from an edge of the substrate to an edge of the first gas barrier layer is greater than a thickness of the first gas barrier layer.