A magnetoresistive element of the present invention includes a multilayer structure that includes a non-magnetic layer (3) and a pair of ferromagnetic layers (1, 2) stacked on both sides of the non-magnetic layer (3). A resistance value differs depending on a relative angle between the magnetization directions of the ferromagnetic layers (1, 2) at the interfaces with the non-magnetic layer (3). The composition of at least one of the ferromagnetic layers (1, 2) in a range of 2 nm from the interface with the non-magnetic layer (3) is expressed by (MxOy)1-zZz, where Z is at least one element selected from the group consisting of Ru, Os, Rh, Ir, Pd, Pt, Cu, Ag, and Au, M is at least one element selected from the group consisting of elements other than Z and O and includes a ferromagnetic metal, and x, y, and z satisfy 0.33