A liquid crystal display device with a high aperture ratio is provided. A liquid crystal display device with low power consumption is provided. A display device includes a liquid crystal element, a transistor, a scan line, and a signal line. The liquid crystal element includes a pixel electrode, a liquid crystal layer, and a common electrode. The scan line and the signal line are each electrically connected to the transistor. The scan line and the signal line each include a metal layer. The transistor includes a metal oxide layer, a gate, and a gate insulating layer. The metal oxide layer includes a first region and a second region. The first region overlaps with the gate with the gate insulating layer therebetween. The second region includes a first part connected to the pixel electrode. The resistivity of the second region is lower than that of the first region. The pixel electrode, the common electrode, and the first part are configured to transmit visible light. The visible light passes through the first part and the liquid crystal element and is emitted to the outside of the display device.