The present invention provides a memory device in which a lower electrode, a seed layer, synthetic antiferromagnetic layers, a separation layer, a magnetic tunnel junction, a capping layer, and an upper electrode are formed on a substrate in a laminated manner, wherein a diffusion barrier is formed between the magnetic tunnel junction and the capping layer. In addition, the present invention provides a memory device in which a lower electrode, a seed layer, synthetic antiferromagnetic layers, a separation layer, a magnetic tunnel junction, a capping layer, and an upper electrode are formed on a substrate in a laminated manner, wherein the seed layer is formed of a material that allows the synthetic antiferromagnetic layers to grow in the FCC (111) direction.