A data writing method for a semiconductor memory device includes writing data into the first memory cell, rewriting the data into the first memory cell when an insufficiency of the data of the first memory cell is determined as a result of verifying the data of the first memory cell at one first reference threshold voltage, writing data into the second memory cell following writing the data into the first memory cell, and rewriting the data into the first memory cell following writing the data into the second memory cell when an insufficiency of the data of the first memory cell is determined as a result of verifying the data of the first memory cell at one second reference threshold voltage. The first reference threshold voltage is set to be different from the second reference threshold voltage.