It is made possible to provide a magnetoresistive effect element that can reverse magnetization direction with a low current, having low areal resistance (RA) and a high TMR ratio. A magnetoresistive effect element includes: a film stack that includes a magnetization free layer including a magnetic layer in which magnetization direction is changeable, a magnetization pinned layer including a magnetic layer in which magnetization direction is pinned, and an intermediate layer provided between the magnetization free layer and the magnetization pinned layer, the intermediate layer being an oxide containing boron (B) and an element selected from the group consisting of Ca, Mg, Sr, Ba, Ti, and Sc. Current is applied bidirectionally between the magnetization pinned layer and the magnetization free layer through the intermediate layer, so that the magnetization of the magnetization free layer is reversible.