Nonvolatile memory device and method of erasing the same

A nonvolatile memory device includes a substrate, a plurality of memory cells stacked in a direction perpendicular to the substrate, word lines connected to the memory cells, a ground select transistor between the memory cells and the substrate, a ground select transistor between the memory cells and the substrate, a ground select line connected to the ground select transistor, a bit line on the memory cells, and a string select transistor between the memory cells and the bit line. In an erase operation, the ground select line is floated at a time when a specific time passes after the erase voltage is provided to the substrate. And the ground select line is floated at different times depending on a temperature.