A data recording device. A random data generator randomly generates substitute data. A recording data generator receives original data and a recording address from a host, receives the substitute data, compares the recording address with a reference address, and outputs the substitute data according to the comparison result. An encoder generates a first data block according to the substitute data. A modulator modulates the first data block. An optical pickup records the modulated first data block on the optical recording medium according to the recording address.