A semiconductor device includes a first insulating layer having a first side wall, an oxide semiconductor layer located on the first side wall, a gate insulating layer located on the oxide semiconductor layer, the oxide semiconductor layer being located between the first side wall and the gate insulating layer, a gate electrode facing the oxide semiconductor layer located on the first side wall, the gate insulating layer being located between the oxide semiconductor layer and the gate electrode, a first electrode located below the oxide semiconductor layer and connected with one portion of the oxide semiconductor layer, and a second electrode located above the oxide semiconductor layer and connected with the other portion of the oxide semiconductor layer.