A display device includes a first substrate having a light shielding layer, and a second substrate having a first metal layer, a semiconductor layer formed over the first metal layer, and a second metal layer formed over the semiconductor layer. A sealing member fixes the first substrate and the second substrate, with a first scale mark formed over the first substrate, and a second scale mark formed over the second substrate and which forms a pair with the first scale mark. The light shielding layer has a first opening portion, and the first scale mark is arranged inside the first opening portion. The second scale mark is formed of a first part of the second metal layer, and a first part of the semiconductor layer and a first part of the first metal layer are overlapped with and extend off from the first part of the second metal.