A magneto-resistive effect element body 11 and a hard magnetic layer 12 for applying a bias magnetic field are disposed between opposing first and second magnetic shields 21 and 22, each made of a soft magnetic material. This magneto-resistive effect element body 11 is comprised of a lamination layer structure portion in which there are laminated at least a free layer the magnetization of which is rotated in response to an external magnetic field, a fixed layer, an antiferromagnetic layer for fixing the magnetization of the fixed layer and a spacer layer interposed between the free layer and the fixed layer. Then, the magneto-resistive effect element has a CPP type configuration in which a sense current flows to the magneto-resistive effect element body in the direction intersecting the film plane of the lamination layer film. Further, a detection magnetic field is introduced in the direction extending along the film plane direction of the lamination layer film and a bias magnetic field is applied in substantially the direction intersecting the direction in which the above-mentioned detection magnetic field is introduced and in the direction extending along the film plane. In this configuration, under the condition that the detection magnetic field is not applied to the magneto-resistive effect element, magnetic fields substantially applied to the front end and the rear end of the side in which the detection magnetic field is introduced, to be concrete, magnetic fields determined mainly by an induced magnetic field HI induced by the above-mentioned sense current and a bias magnetic field HB are set to the same directions, particularly, in the free layer, whereby a single magnetic domain is nucleated in the free layer with high stability.