According to one embodiment, a semiconductor device includes a first conductive layer between first and second insulating layers with an oxide semiconductor column extending in the first direction through these layers. A third insulating layer covers the column. The column has a first semiconductor portion at a first position matching the first insulating layer, a second semiconductor portion at a second position matching second insulating layer, and a third semiconductor portion at a third position matching the first conductive layer. The first semiconductor portion is continuous along a second direction between the third insulating layer, the second semiconductor portion is continuous along the second direction between the third insulating layer, but the third semiconductor portion is not continuous between the third insulating layer.