A magnetoresistance effect element has a lamination structure comprising a
free layer including two ferromagnetic layers, a pinned layer including
two ferromagnetic layers, and at least one nano-contact portion composed
of a single ferromagnetic layer and disposed at least one portion between
the free layer and the pinned layer. A distance between the free layer
and the pinned layer, i.e., thickness of the nano-contact portion in the
lamination direction, is not more than Fermi length, preferably less than
100 nm.