Provided is a driving method of a nonvolatile memory device for performing a write operation using a plurality of consecutive write loops. The driving method includes writing data to a plurality of nonvolatile memory cells during a first write loop, and after the first write loop, writing the data to the plurality of nonvolatile memory cells during a second write loop. A first maximum parallel bit size of the first write loop is n bits. A second maximum parallel bit size of the second write loop is m bits. m is greater than n.