An operating method of a nonvolatile memory device includes determining whether a memory block is a selected block, and when the memory block is not the selected block, determining whether the memory block shares a block word line with the selected block. The method further includes applying an unselected block word line voltage to word lines of the memory block when the memory block shares the block word line with the selected block, and floating the word lines of the memory block when the memory block does not share the block word line with the selected block.