Abstract: A multiple byte wide parallel write circuit having a number of cell array blocks for storing data, and a plurality of data input buffers includes a plurality of data bus selectors for selecting data buses, a plurality of clock pulse generators for generating clock signals for an individual data input driver on the basis of a test mode enable signal and a column/row address signal, and a plurality of individual data input drivers for driving respective outputs of the data bus selectors and for applying the output driven to the entire input/output (I/O) lines at the same time. Thereby, the improvement may write into the memory cell arrays the data having a greater number of bit lines than that of the data buses, without increasing the layout area nor increasing the load on the bus lines.