According to one embodiment, a semiconductor storage device includes: first and second plate-shaped portions which extend in a stacking direction of each layer of a first stacked body and a first direction intersecting the stacking direction and are arranged between the first stacked body and a second stacked body on both sides of the second stacked body in a second direction intersecting the stacking direction and the first direction; and an isolation layer that penetrates at least the uppermost conductive layer among a plurality of conductive layers and isolates the uppermost conductive layer in the second direction. The isolation layer extends in a portion of the first stacked body in the first direction toward the second stacked body, and is connected to a side surface of the first plate-shaped portion from a first region on an inner side of the first and second plate-shaped portions.