A magnetic position detection device comprising: a bias magnet producing a bias magnetic field having first and second magnetic pole surfaces which are parallel to each other and which have respective opposite single magnetic polarities; an object magnet spaced from the bias magnet, producing an object magnetic field and moving along a movement direction, wherein the object magnet has first and second magnetic pole surfaces which are parallel to each other and which have respective opposite single magnetic polarities, the second magnetic pole surface of the bias magnet faces the first magnetic pole surface of the object magnet, the first and second magnetic pole surfaces of the bias magnet are parallel to the first and second magnetic pole surfaces of the object magnet and are parallel to the movement direction of the object magnet; and a magnetic field detection element to which the bias magnetic field produced by the bias magnet and the object magnetic field produced by the object magnet are applied, as an applied magnetic field, wherein the magnetic field detection element is located between the second magnetic poled surface of the bias magnet and the first magnetic poled surface of the object magnet, is fixed in position relative to the bias magnet, and detects direction of the applied magnetic field, movement of the object magnet in position relative to the bias magnet along the movement direction changes the direction of the applied magnetic field so that the direction of the applied magnetic field detected by the magnetic field detection element uniquely identifies the position of the object magnet along the movement direction, and when, in the movement of the object magnet relative to the bias magnet, along the movement direction, the object magnet reaches a point that is closest to the bias magnet, the object magnetic field is larger at the magnetic field detection element than the bias magnetic field at the magnetic field detection element, and when, in the movement of the object magnet relative to the bias magnet, along the movement direction, the object magnet is directly opposite the bias magnet, the magnetic field detection element is closer to the object magnet than to the bias magnet. a bias magnet producing a bias magnetic field having first and second magnetic pole surfaces which are parallel to each other and which have respective opposite single magnetic polarities; an object magnet spaced from the bias magnet, producing an object magnetic field and moving along a movement direction, wherein the object magnet has first and second magnetic pole surfaces which are parallel to each other and which have respective opposite single magnetic polarities, the second magnetic pole surface of the bias magnet faces the first magnetic pole surface of the object magnet, the first and second magnetic pole surfaces of the bias magnet are parallel to the first and second magnetic pole surfaces of the object magnet and are parallel to the movement direction of the object magnet; and a magnetic field detection element to which the bias magnetic field produced by the bias magnet and the object magnetic field produced by the object magnet are applied, as an applied magnetic field, wherein the magnetic field detection element is located between the second magnetic poled surface of the bias magnet and the first magnetic poled surface of the object magnet, is fixed in position relative to the bias magnet, and detects direction of the applied magnetic field, movement of the object magnet in position relative to the bias magnet along the movement direction changes the direction of the applied magnetic field so that the direction of the applied magnetic field detected by the magnetic field detection element uniquely identifies the position of the object magnet along the movement direction, and when, in the movement of the object magnet relative to the bias magnet, along the movement direction, the object magnet reaches a point that is closest to the bias magnet, the object magnetic field is larger at the magnetic field detection element than the bias magnetic field at the magnetic field detection element, and when, in the movement of the object magnet relative to the bias magnet, along the movement direction, the object magnet is directly opposite the bias magnet, the magnetic field detection element is closer to the object magnet than to the bias magnet.