A magnetoresistanee effect element comprises a free layer composed of a ferromagnetic layer, a pinned layer composed of a ferromagnetic layer, and a layer disposed between the free layer and the pinned layer and including at least one nano-contact portion disposed between the free layer and the pinned layer. The nano-contact portion has a dimension, including at least one of a length in the layer lamination direction and a length in a direction normal to the layer lamination direction, being not more than Fermi length. The nano-contact portion is provided, in an inside portion thereof, with a magnetic wall composed of either one of Bloch magnetic wall, Neel magnetic wall or a combination wall thereof.