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 which has a plurality of magnetic domains, a current applying unit which applies current for a magnetic domain wall movement to the magnetic layer, and a head for reading and writing, wherein the magnetic layer comprises a plurality of perpendicular magnetic layers formed on a substrate in a plurality of rows and columns, and a horizontal magnetic layer formed on the perpendicular magnetic layers to connect the perpendicular magnetic layers.