A semiconductor device with high aperture ratio is provided. The semiconductor device includes a nitride insulating film, a transistor over the nitride insulating film, and a capacitor including a pair of electrodes over the nitride insulating film. An oxide semiconductor layer is used for a channel formation region of the transistor and one of the electrodes of the capacitor. A transparent conductive film is used for the other electrode of the capacitor. One electrode of the capacitor is in contact with the nitride insulating film, and the other electrode of the capacitor is electrically connected to one of a source electrode and a drain electrode of the transistor.