Provided is an MR effect element in which the magnetization of the pinned
layer is stably fixed even after going through high temperature process.
The MR effect element comprises: a non-magnetic intermediate layer; a
pinned layer and a free layer stacked so as to sandwich the non-magnetic
intermediate layer; an antiferromagnetic layer stacked to have a surface
contact with the pinned layer, for fixing a magnetization of the pinned
layer to a direction in-plane of the pinned layer and perpendicular to a
track width direction; and hard bias layers provided on both sides in the
track width direction of the free layer, for applying a bias field to the
free layer, a product .lamda..sub.S.times..sigma. of a saturation
magnetostriction constant .lamda..sub.S of the pinned layer and an
internal stress .sigma. on a cross-section perpendicular to a layer
surface of the hard bias layer being negative.