A semiconductor memory device comprises a memory cell array, at least one redundant cell control, a sense amplifier, and at least one redundant cell. The memory cell array receives and outputs data through data I/O line groups. The redundant cell control stores a defective cell address, generates a redundant cell enable control signal when the defective cell address is equal to an input cell address, generates a redundant cell read control signal during a read operation in response to the redundant cell enable control signal, and generates a redundant cell write control signal during a write operation in response to the redundant cell enable control signal. The sense amplifier is connected to an I/O line group commonly connected to the data I/O line groups, amplifies and outputs data outputted from the memory cell array during the read operation, and is disabled in response to the redundant cell read control signal. The redundant cell stores input data transferred to the I/O line group in response to the redundant cell write control signal and outputs stored data in response to the redundant cell read control signal.