A nonvolatile memory device, including a first latch unit and a nonvolatile memory cell, and a method of writing data in a nonvolatile memory device are provided. The method includes receiving a first writing command or a second writing command from outside of the nonvolatile memory device, and writing first data stored in the first latch unit in the nonvolatile memory cell in response to the first or second writing command. The first data is retained in the first latch unit until the writing of the first data stored in the first latch unit in the nonvolatile memory cell is completed.