A semiconductor storage device includes a substrate, a plurality of first gate electrodes on the substrate and arranged in a thickness direction of the substrate, and a first semiconductor pillar extending in the thickness direction of the substrate through the plurality of first gate electrodes, the first semiconductor pillar including a first portion facing the plurality of first gate electrodes and a second portion farther from the substrate than the first portion. The semiconductor storage device also includes a second gate electrode on the substrate farther from the substrate than the plurality of first gate electrodes, and a second semiconductor pillar extending in the thickness direction of the substrate through the second gate electrode, and connected to the first semiconductor pillar at the second portion of the first semiconductor pillar. The second portion of the first semiconductor pillar contains carbon (C).