A magneto-resistance effect element comprises a stacked body which comprises a pinned layer having a fixed magnetization direction, a free layer having a magnetization direction that varies according to an external magnetic field, and a nonmagnetic spacer layer which is interposed between the pinned layer and the free layer. The stacked body having a constricted shape in which at least one part of the spacer layer is constricted when viewed from at least one direction perpendicular to a stacked direction of the stacked body.