Abstract: A dynamic semiconductor memory device comprises a memory array by which memory-cell units having a plurality of dynamic type memory cells connected in series are arranged in a matrix. Sense-amplifier circuits compare and amplify potential difference of a pair of data lines connected to the memory-cell units. Sense amplifier drivers charge or discharge the data lines. The memory further comprises means for changing drive capacity of the sense amplifier driver during reading-out and either restoring or writing. For example, by making the restoring or writing drive capacity smaller than the reading drive capacity, electric charge or discharge peak currents of the data lines line can be reduced.