A data storage device includes a nonvolatile memory device configured to include a plurality of pages; and a controller configured to control an operation of the nonvolatile memory device, wherein the controller stores first data in a first least significant bit (LSB) page, stores the first data in a first most significant bit (MSB) page which is coupled to the same first word line as the first LSB page, when a first condition is satisfied, and stores second data in the first MSB page after the first data is stored in the first MSB page.