A magnetoresistive effect device includes a first ferromagnetic layer having a fixed magnetization direction and having magnetic moment ml per unit area. A nonmagnetic layer contacts with the first ferromagnetic layer and has an amplitude hi of roughness of an interface between the nonmagnetic layer and the first ferromagnetic layer. A second ferromagnetic layer contacts with the nonmagnetic layer, has a fixed magnetization direction, has magnetic moment m2 per unit area which is smaller than the magnetic moment m1, and has an amplitude h2 of roughness of an interface between the second ferromagnetic layer and the nonmagnetic layer. A barrier layer contacts with the second ferromagnetic layer, and has an amplitude h3, which is smaller than the amplitudes h1 and h2, of roughness of an interface between the barrier layer and the second ferromagnetic layer. A third ferromagnetic layer contacts with the barrier layer and has a variable magnetization direction.