To provide a semiconductor device capable of retaining data for a long time. The semiconductor device includes a first transistor, an insulator covering the first transistor, and a second transistor over the insulator. The first transistor includes a first gate electrode, a second gate electrode overlapping with the first gate electrode, and a semiconductor between the first gate electrode and the second gate electrode. The first gate electrode is electrically connected to one of a source and a drain of the second transistor.