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[Problem] To provide a high-precision proximity sensor not adversely affected by variations in magnets. [Solution] A first yoke is insert-molded between the north and south magnetic pole end surfaces of a rare-earth bonded magnet (10) during injection molding, and a projection (22) of the first yoke projects from a wall surface perpendicular to the magnetic pole end surfaces (12). A protrusion (32) of a second yoke (30) faces the projection (22), and the main unit (31) is arranged parallel to the wall surface of the magnet (10). A Hall IC (40) is arranged in a space between the projection (22) and the protrusion (32) so the direction of a line connecting the projection and the protrusion is in the direction of magnetic induction. When a component to be detected (50) is away from a magnetic pole end surface (12), the magnetic flux crosses the direction of magnetic induction, but the magnetic flux flows from the component to be detected (50) in the direction of magnetic induction between the projection (22) and the protrusion (32) near a magnetic pole end surface (12), and the change in magnetic flux density is detected with high sensitivity by the Hall IC (40). Because only a single magnet (10) is provided, the sensor is not adversely affected by variations in a plurality of magnets or by variations in the mounting of a plurality of magnets.