A nonvolatile memory device having a multi-stack memory block includes: a memory cell array divided into a plurality of memory stacks disposed in a vertical direction; and a control circuit configured to perform a channel voltage equalization operation of the plurality of memory stacks, wherein inter-stack portions are between the plurality of memory stacks, and a channel hole passes through the word lines of each of the plurality of memory stacks. The control circuit determines, as inter-stack word lines, some word lines adjacent to the inter-stack portions among the word lines of each of the plurality of memory stacks and differently controls setup time points for applying a pass voltage, or recovery time points for applying a ground voltage, to the inter-stack word lines, according to sizes of the channel hole of the inter-stack word lines.