Abstract: In a dynamic random access memory including a plurality of memory read circuit arrays, a sense amplifier has a circuit wherein a first switch (or a pair of first switches) and a pair of second switches connected in series to the first switch are connected between the common data lines and the common source line of a second precharger. The first switch is controlled according to the potential of the bit lines precharged by a first precharger, while the second switches are controlled according to the address signal. Further, a third switch is provided to connect the common source line to an activation potential for the common source line in the memory array not selected. A second precharger precharges the common source line in a memory array not selected to a second precharge potential and the common data lines in a memory array not selected to a third precharge potential during the time when the common source line and the common data lines are not selected.