A semiconductor device includes first and second gate electrodes, a semiconductor layer between the first and second gate electrodes and extending along a first direction, a first gate insulating layer between the first gate electrode and the semiconductor layer, a second gate insulating layer between the second gate electrode and the semiconductor layer, a first insulating layer including a first region adjacent to the first gate electrode in the first direction and contacting the semiconductor layer, and a second insulating layer extending including a second region adjacent to the second gate electrode in the first direction and contacting the semiconductor layer. An interface between the first region and the semiconductor layer in a direction crossing the first direction is adjacent to the first gate electrode in the first direction.