Nonvolatile memory device with capability of determining degradation of data erase characteristics

A nonvolatile memory device includes a memory cell region and a peripheral circuit region. The memory cell region includes a memory block, and the peripheral circuit region includes a control circuit. The memory cell region includes a first metal pad. The peripheral circuit region includes a second metal pad and is vertically connected to the memory cell region by the first metal pad and the second metal pad. The memory block includes a plurality of memory cells disposed in a vertical direction. The control circuit determines whether a data erase characteristic for the memory block is degraded for each predetermined cycle of data erase operation, and performs a data erase operation by changing a level of a voltage applied to selection transistors for selecting the memory block as an erase target block when it is determined that the data erase characteristic is degraded.