1. A data writing method for a semiconductor memory device having a first memory cell block capable of rewriting data and having at least one first memory cell; and a second memory cell block capable of rewriting data and having at least one second memory cell adjoining said first memory cell, said method comprising: writing data into said first memory cell; writing data into said second memory cell following writing the data into said first memory cell; verifying the data of said first memory cell after writing the data into said second memory cell; and rewriting the data into said first memory cell when insufficiency of the data of said first memory cell as a result of verifying the data of said first memory cell.