A display device includes a pixel portion in which a pixel electrode layer is arranged in a matrix, and an inverted staggered thin film transistor having a combination of at least two kinds of oxide semiconductor layers with different amounts of oxygen is provided corresponding to the pixel electrode layer. In the periphery of the pixel portion in this display device, a pad portion is provided to be electrically connected to a common electrode layer formed on a counter substrate through a conductive layer made of the same material as the pixel electrode layer. One objection of our invention to prevent a defect due to separation of a thin film in various kinds of display devices is realized, by providing a structure suitable for a pad portion provided in a display panel.