A semiconductor memory device includes a substrate that has a first main surface and a second main surface opposite to the first main surface, a first semiconductor chip which is mounted on the first main surface and includes a first register, a plurality of first input/output (IO) terminals, and a first circuit connected between the first IO terminals and the first register, and a second semiconductor chip which is mounted on the second main surface and includes a second register, a plurality of second input/output (IO) terminals, and a second circuit connected between the second IO terminals and the second register. The second circuit is connected to the second IO terminals through input lines and to the second register through output lines, and is configured to change a connection path between the input lines and the output lines in response to a connection change command.