Provided are a data storage device using a magnetic domain wall movement and a method of operating the data storage device. The data storage device includes a magnetic layer including a plurality of magnetic domains, first and second ferromagnetic pinned layers formed on lower and upper surfaces of the magnetic layer, respectively, and having opposite magnetization directions, first and second insulating spacers interposed between the first and second ferromagnetic pinned layers and the magnetic layer, respectively, and an energy supplying unit applying energy to the magnetic layer for a magnetic domain wall movement.