A nonvolatile semiconductor memory device in an embodiment includes a semiconductor layer, a memory cell array, word lines, bit lines, a source line, and a control circuit. The memory cell array has memory strings, each of the memory strings having memory cells. The word lines are connected to the control gates of the memory cells. The control circuit controls a voltage applied to the semiconductor layer, the control gates, the bit lines, and the source line. When executing a read operation, the control circuit begins application of a first voltage to the source line at a first time, the first voltage having a positive value. The control circuit begins application of a second voltage to unselected word lines at the first time or thereafter, the second voltage setting the memory cells to a conductive state regardless of retained data of the memory cells.