Spin current magnetization reversal element, magnetoresistance effect element, and magnetic memory

This spin current magnetization reversal element comprises: a first ferromagnetic metal layer that has a variable magnetization direction; and spin orbit torque wiring that is joined to a first surface of the first ferromagnetic metal layer and that extends in a second direction that intersects a first direction, which is the direction normal to the first ferromagnetic metal layer. The spin orbit torque wiring comprises: a pure spin current generating part that is joined to the first ferromagnetic metal layer; and a low-resistance part that is connected to both second-direction ends of the pure spin current generating part 2A and that comprises a material that has a lower electrical resistivity than the pure spin current generating part. The pure spin current generating part is formed such that the area of a cross-section thereof that is orthogonal to the first direction increases continuously or in stages in the first direction with increasing distance from a joining surface that is joined to the first ferromagnetic metal layer.