An object is to provide a display device with low power consumption and good display quality. A first substrate is provided with a terminal portion, a pixel electrode, a switching transistor including an oxide semiconductor, a first optical sensor having high optical sensitivity to visible light, and a second optical sensor having optical sensitivity to infrared light and having lower optical sensitivity to visible light than the first optical sensor. The illuminance or color temperature around a display device is detected using the first and second optical sensors, and the luminance or color tone of a display image is adjusted. A second substrate is provided so as to face the first substrate, and is provided with a counter electrode. In a period for displaying a still image, the switching transistor is turned off so that the counter electrode is brought into a floating state.