Semiconductor memory device

A first input buffer receives sequentially inputted first data. A first data selector selectively transfers the first data from the first input buffer in accordance with a data input mode. A first data alignment circuit aligns and outputs the data from the first data selector. A second input buffer receives sequentially inputted second data in accordance with the data input mode. A second data selector selectively transfers the data of the first input buffer or of the second input buffer, in accordance with the data input mode. A first data alignment circuit aligns and outputs the data from the second data selector.