A semiconductor memory device includes first and second bus regions, a third bus region laid out along a center line, a first cell region laid out between a first side and the first bus region, a second cell region laid out between a second side and the second bus region, third and fourth cell regions laid out between the first and second bus regions and laid out toward a third side and a fourth side respectively seen from the third bus region, and a data input/output pad string laid out along the third bus region.