A semiconductor memory device may include a power line, an over driver, and/or an internal voltage driver. The power line may be connected to at least one sense amplifier. The at least one sense amplifier may be connected to a memory cell included in a memory block. The memory block may be included in one of a plurality of memory block units including one or more memory blocks. The over driver may be configured to apply an external voltage to the power line in a sensing period of the sense amplifier. The internal voltage driver may be configured to apply an internal voltage to the power line in an amplification period of the sense amplifier. The over driver may be configured to perform an over driving operation by each memory block unit.