The invention provides a novel display device. The display device includes a pixel portion, a driver circuit portion that is provided outside the pixel portion, and a protection circuit that is electrically connected to one of or both the pixel portion and the driver circuit portion and includes a pair of electrodes. The pixel portion includes pixel electrodes arranged in a matrix and transistorselectrically connected to the pixel electrodes. The transistor includes a first insulating layer containing nitrogen and silicon, and a second insulating layer containing oxygen, nitrogen, and silicon. The protection circuit includes the first insulating layer between the pair of electrodes.