Abstract: A dynamic semiconductor memory device comprising a plurality of memory blocks each including a sense amplifier array and a pair of memory cell groups, a row decoder for selecting a row line within the plurality of memory blocks, a column decoder which is common to the plurality of memory blocks and which selectively connects a sense amplifier in each of the memory blocks to a corresponding one of the pairs of bus lines. The device also includes row block decoders which selectively enable the sense amplifier array of one of the memory blocks according to block selecting address signals, and block bus line decoders which selectively connect the pair of bus lines of each of the memory blocks to a pair of data buses according to the block selecting address signals.