An operating method of a nonvolatile memory device is provided which sequentially performs a plurality of erase loops to erase at least one of a plurality of memory blocks. The operating method comprises performing at least one of the plurality of erase loops; performing a post-program operation on the at least one memory block after the at least one erase loop is executed; and performing remaining erase loops of the plurality of erase loops. The post-program operation is not performed when each of the remaining erase loops is executed.