A semiconductor memory device includes a memory cell array including a plurality of word lines, a plurality of bit lines including complementary pairs of bit lines, and a plurality of memory cells storing data; a sense amplifier coupled to the memory cell array and configured to sense voltage differences between the complementary pairs of bit lines and amplify the voltage differences; and at least one voltage driver configured to provide either a predetermined voltage or a first power supply voltage to the memory cell array to increase a sensing margin of the semiconductor memory device. The semiconductor memory device increases respective potential differences between complementary pairs of bit lines using a voltage isolated in the memory cell array.