A semiconductor device of one embodiment of the present invention includes a semiconductor, an insulator, a first conductor, and a second conductor. In the semiconductor device, a top surface of the semiconductor has a region in contact with the insulator; a side surface of the semiconductor has a region in contact with the insulator; the first conductor has a first region overlapping with the semiconductor with the insulator positioned therebetween; the first region has a region in contact with the top surface of the semiconductor and a region in contact with the side surface of the semiconductor; the second conductor has a second region in contact with the semiconductor; and the first region and the second region do not overlap with each other.