A semiconductor memory device includes a selection transistor on a semiconductor substrate, a lower contact plug connected to a drain region of the selection transistor, and a magnetic tunnel junction pattern on the lower contact plug, the magnetic tunnel junction pattern including a bottom electrode in contact with the lower contact plug, the bottom electrode being an amorphous tantalum nitride layer, a top electrode on the bottom electrode, first and second magnetic layers between the top and bottom electrodes, and a tunnel barrier layer between the first and second magnetic layers.