A semiconductor device includes a first semiconductor layer that is an electrically-conductive polycrystalline semiconductor layer and a second semiconductor layer on the first semiconductor layer. The second semiconductor layer is an electrically-conductive polycrystalline semiconductor layer having a smaller average grain size than the first semiconductor layer. A plurality of electrode layers are stacked on the second semiconductor layer at intervals in a first direction. A third semiconductor layer extends in the first direction through the first semiconductor layer, the second semiconductor layer, and each of the electrode layers and contacts the second semiconductor layer. A charge storage layer is between the plurality of electrode layers and the third semiconductor layer.