According to one embodiment, a semiconductor device, includes a magneto resistive element including a first magnetic layer, a first interface magnetic layer, a nonmagnetic layer, a second interface magnetic layer and a second magnetic layer as a stacked structure in order; and a metal layer including first metal atoms, second metal atoms and boron atoms, the metal layer being provided at least one region selected from under the first magnetic, between the first magnetic layer and the first interface magnetic layer, between the second interface magnetic layer and the second magnetic layer, and upper the second magnetic layer.