A magneto-resistive effect element includes a free layer having a magnetization direction which varies with respect to an external magnetic field; a pinned layer which includes a stacked structure comprising an outer pinned layer which has a magnetization direction that is fixed with respect to the external magnetic field, a non-magnetic intermediate layer which is made of ruthenium with a thickness of about 0.4 nm, and an inner pinned layer with a thickness of 3 nm or more, wherein the inner pinned layer has a magnetization direction which is fixed with respect to the external magnetic field due to anti-ferromagnetic coupling with the outer pinned layer via the non-magnetic intermediate layer; and a spacer layer sandwiched between the free layer and the inner pinned layer. Sense current flows through the pinned layer, the spacer layer, and the free layer substantially in a stacked direction.