A display device includes a pixel portion including a plurality of pixels each including a first transistor, a second transistor, and a light-emitting element, in which a gate of the first transistor is electrically connected to a scan line, one of a source and a drain of the first transistor is electrically connected to a signal line, and the other of them is electrically connected to a gate of the second transistor; one of a source and a drain of the second transistor is electrically connected to a power supply line and the other of them is electrically connected to the light-emitting element, and the first transistor includes an oxide semiconductor layer. A period when the display device displays a still image includes a period in which output of a signal to all the scan lines in the pixel portion is stopped.