A semiconductor memory device comprises a memory cell array and a data inversion circuit. The data inversion circuit is configured to receive a first unit data and a second unit data stored in the memory cell array through different first data lines, determine, while the first unit data is transmitted to a data input/output (I/O) buffer through a second data line, whether to the invert the second unit data based on a Hamming distance between the first unit data and the second unit data, and transmit the inverted or non-inverted second unit data to the data I/O buffer through the second data line.