The invention provides a magnetoresistive element in which a pinned magnetic layer (15 or 17) includes at least one non-magnetic film and magnetic films, and the magnetic films are coupled with one another by magnetostatic coupling. Furthermore, the invention provides a magnetoresistive element in which the magnetic films in the pinned magnetic layer (15 or 17) are coupled with on another by magnetostatic or antiferromagnetic coupling generating negative magnetic coupling. Furthermore, the invention provides a magnetoresistive element in which at least one of the magnetic layers (15, 17) includes an oxide ferrite having a plane orientation with a (100), (110) or (111) plane. A magnetic field is introduced in the plane. This oxide can be formed by sputtering with an oxide target while applying a bias voltage to a substrate including a plane on which the oxide ferrite is to be formed so as to adjust the amount of oxygen supplied to the oxide ferrite.