<p>PURPOSE: A nonvolatile memory and an erasing method thereof are provided to improve the reliability of an erase operation by stably transmitting an erase voltage to a surface layer of a pillar. CONSTITUTION: An erase voltage(Vers) is applied to a substrate. A selection word line voltage(Vsw) is applied to word lines connected to a selected sub block of a selected memory block. After a non-selection word line voltage(Vusw) is applied to word lines connected to an unselected sub block of the selected memory block for the first delay time from an application point of the erase voltage, the word lines connected to the unselected sub block are floated.</p>
