Method of controlling initialization of nonvolatile memory device, where nonvolatile memory device includes memory cell region including first metal pad and peripheral circuit region including second metal pad and vertically connected to memory cell region by first and second metal pads, includes performing first sensing operation to sense write setting data stored in first memory cells in memory cell region of first memory plane and store first read setting data in first page buffer circuit in peripheral circuit region of first memory plane, performing second sensing operation to sense write setting data stored in second memory cells in memory cell region of second memory plane and store second read setting data in second page buffer circuit in peripheral circuit region of second memory plane and performing dump-down operation to store restored setting data in buffer based on first read setting data and second read setting data.