A semiconductor memory device and a method for writing and reading data to and from the same comprises a memory cell array including a plurality of memory cells connected between a plurality of word lines and a plurality of bit line pairs, a predetermined number of write line pairs, a predetermined number of read line pairs, a plurality of write column selection gates for transmitting data between the plurality of bit line pairs and the predetermined number of write line pair during a write operation, and a plurality of read column selection gates for transmitting data between the plurality of bit line pairs and the predetermined number of read line pairs during a read operation. Accordingly, it is possible to input and output data simultaneously through data input pads and data output pads.