A pair of bias magnets applies a bias magnetic field to the magneto-resistive effect element, the bias magnetic field having a component in a direction such that the component cancels the external magnetic field that is applied to the magneto-resistive effect element and a component that is perpendicular to the external magnetic field. The bias magnet has an elongate cross section in a plane that is parallel both to the external magnetic field and to the bias magnetic field. In a projection plane that is parallel to the cross section and onto which the bias magnets and the magneto-resistive effect element are projected, the bias magnet includes an element facing side that is opposite to the magneto-resistive effect element and that extends in a longitudinal direction. The bias magnet is magnetized in a direction that is perpendicular to the longitudinal direction. The element facing side is longer than other sides.