A method of fabricating a magnetic memory device is provided. The method may include sequentially forming a first magnetic layer, a tunnel barrier layer, and a second magnetic layer on a substrate, forming a mask pattern on the second magnetic layer to expose a portion of the second magnetic layer, forming a capping insulating layer on a sidewall of the mask pattern and the portion of the second magnetic layer, injecting an oxygen ion into the portion of the second magnetic layer through the capping insulating layer to form an oxide layer, anisotropically etching the capping insulating layer to form a capping spacer, and patterning the oxide layer, the tunnel barrier layer, and the first magnetic layer using the mask pattern and the capping spacer.