A semiconductor memory device includes a first semiconductor layer that includes a first part extending in a first direction, a second part extending in the first direction, and a third part connected to the first and second parts. When a cross-sectional surface extending in second and third directions and including the third part is defined as a first cross-sectional surface, the third part has one side and the other side of an imaginary center line in the third direction in the first cross-sectional surface defined as first and second regions, the third part has maximum widths in the second direction in the first and second regions defined as first and second widths, and the third part has a width in the second direction on the imaginary center line defined as a third width, the third width is smaller than the first and second widths.