A memory device in which lower electrodes, a buffer layer, a seed layer, a magnetic tunnel junction, a capping layer, synthetic antiferromagnetic layers, and an upper electrode are formed on a substrate in a laminated manner. The lower electrodes and the seed layer are formed of a polycrystalline conductive material, and the perpendicular magnetic anisotropy of the magnetic tunnel junction is maintained upon heat treatment at a high temperature of 400° C. or more.