A magnetic memory device includes a substrate including a cell region and a peripheral circuit region, lower contact plugs on the cell region, data storage structures on the lower contact plugs, and a peripheral interconnection structure on the peripheral circuit region. The peripheral interconnection structure includes a line portion extending in a direction parallel to a top surface of the substrate, and contact portions extending from the line portion toward the substrate. A height of each of the contact portions is less than a height of each of the lower contact plugs.