A semiconductor memory device includes an I/O line for transmitting read data that has been read from a memory cell, a plurality of driver circuits for driving the I/O line on the basis of the read data, a read circuit for receiving the read data transmitted through the I/O line, and an assist circuit for amplifying the read data transmitted through the I/O line. The assist circuit is disposed farther away from a prescribed drive circuit included in the plurality of drive circuits as viewed from the read circuit. The signal level can thereby rapidly change levels even in memories having relatively long I/O lines.