According to one embodiment, a magnetoresistive effect element includes: a nonmagnetic layer; a stacked structure body; and a detection layer. The stacked structure body is provided on the nonmagnetic layer. The stacked structure body includes: a reference layer; an oscillation layer; and an intermediate layer. The reference layer is provided on the nonmagnetic layer. A magnetization of the reference layer is fixed. The oscillation layer is provided on the reference layer. A magnetization of the oscillation layer is substantially parallel to the magnetization of the reference layer and is variable. The intermediate layer is provided between the reference layer and the oscillation layer. The detection layer is provided on the nonmagnetic layer apart from the stacked structure body.