A magnetic memory device includes a reference magnetic pattern having a magnetization direction fixed in one direction, a free magnetic pattern having a changeable magnetization direction, and a tunnel barrier pattern disposed between the free and reference magnetic patterns. The free magnetic pattern has a first surface being in contact with the tunnel barrier pattern and a second surface opposite to the first surface. The magnetic memory device further includes a sub-oxide pattern disposed on the second surface of the free magnetic pattern, and a metal boride pattern disposed between the sub-oxide pattern and the second surface of the free magnetic pattern. The magnetization directions of the free and reference magnetic patterns are substantially perpendicular to the first surface of the free magnetic pattern.