A magnetoelectric converting element is constructed by four or more magnetic resistance segments symmetrically arranged at a predetermined pitch with respect to the central line of a magnet perpendicular to the rotating direction of a magnetic moving body. The magnetizing direction of the magnet is set to the direction perpendicular to the direction opposed to the magnetic moving body. Further, 0.7P≦X≦P and P≦Y≦1.6P are set when the size of the magnet in the moving direction of the magnetic moving body is set to X and the size of the magnet in the direction opposed to the magnetic moving body is set to Y and the pitch of the magnetic resistance segments at both ends constituting the magnetoelectric converting element is set to P.