According to one embodiment, a nonvolatile semiconductor memory device includes: a memory cell array having: a cell string including a plurality of memory cells connected in series; a plurality of word lines respectively connected to the plurality of memory cells; a source side selecting gate connected to one end of the cell string; and a drain side selecting gate connected to the other end of the cell string; a word line selector that selects one of the word lines connected to a target memory cell to be written; and an equalizing unit that equalizes voltages of the plurality of word lines after data write of the target memory cell is finished.