Data storage devices using movement of magnetic domain walls and methods of operating the same are provided. A data storage device includes a magnetic track having a verifying region. Within the verifying region, first and second magnetic domains are arranged alternately. The first magnetic domains correspond to first data and the second magnetic domains correspond to second data. A verification sensor is arranged at an end of the verifying region. A current applying element is configured to apply one or more pulse currents to the magnetic track. A first counter is connected to the verification sensor and configured to count the number of magnetic domains passing through the verification sensor.