A semiconductor memory device includes a controller for sequentially activating first and second control signals and activating a third control signal during an amplification period, in a pseudo cryogenic temperature, a first driver for driving a first power source line with a first voltage during an initial period of the amplification period, based on the first control signal, a second driver for driving the first power source line with a second voltage during a later period of the amplification period, based on the second control signal, a third driver for driving a second power source line with a third voltage during the amplification period, based on the third control signal, and a sense amplifier for primarily amplifying a voltage difference between a data line pair using the first and third voltages during the initial period, and secondarily amplifying the difference using the second and third voltages during the later period.