Disclosed is a method for manufacturing a magnetic memory device. The method for manufacturing a magnetic memory device comprises sequentially forming a first magnetic layer, a tunnel barrier layer, and a second magnetic layer on a substrate, forming a boron absorption layer on the second magnetic layer, sequentially forming a metal capping layer and an oxygen donor layer on the boron absorption layer, and performing a heat treatment process to diffuse at least a portion of oxygen atoms included in the oxygen donor layer into the metal capping layer and the boron absorption layer. The metal capping layer has a greater oxygen diffusivity than the oxygen donor layer.