Provided is a highly integrated semiconductor device which can hold data and includes a NAND cell array. Each of the plurality of memory cells of the NAND cell array includes a first transistor, a second transistor, a first terminal, a second terminal, a third terminal, and a fourth terminal. The first terminal is electrically connected to one electrode connected to a channel region of the first transistor. The second terminal is electrically connected to the other electrode connected to the channel region of the first transistor. The third terminal is electrically connected to a gate electrode of the second transistor. The fourth terminal is electrically connected to one electrode connected to a channel region of the second transistor. A gate electrode of the first transistor is in contact with the other electrode connected to the channel region of the second transistor. A string of the plurality of memory cells is formed by connecting the first terminals and the second terminals.