The present relates to a memory device; and, more particularly, to an apparatus and a method for preventing a loss of reliability of data, which are stored in memory cell, at the time of restoring and writing the data. The semiconductor memory device according to the present invention comprises: a high voltage generator for boosting an external voltage level and then for producing a first high voltage level; a pumping control signal generator for issuing a pumping control signal, which is activated in a restore section and a write section, in response to a command signal; a pumping unit for outputting the first high voltage level from the high voltage generator or for boosting the high voltage level in order to generate a second high voltage plus level in response to the pumping control signal from the pumping control signal generator, wherein the second high voltage plus level is higher than the first high voltage level; and a word line driver for driving the word line WL using the first high voltage level and for driving the word line WL using the second high voltage plus level from the pumping unit in the restore and write sections.