A magnetoresistive effect element, which includes: a first ferromagnetic layer as a magnetization fixed layer; a second ferromagnetic layer as a magnetization free layer; and a nonmagnetic spacer layer provided between the first ferromagnetic layer and the second ferromagnetic layer. The nonmagnetic spacer layer includes an Ag alloy represented by General Formula (1), and thereby lattice mismatch between the nonmagnetic spacer layer, and the first ferromagnetic layer and/or the second ferromagnetic layer is reduced, compared to lattice mismatch when the nonmagnetic spacer layer is formed of Ag, AgγX1-γ  (1) where X indicates one element selected from the group made of Al, Cu, Ga, Ge, As, Y, La, Sm, Yb, and Pt, and 0