In a magnetic rotor, a rotatable shaft is received through a holder. A positioner is made of a magnetic material and is fitted into at least one of an outer peripheral wall of the rotatable shaft and an inner peripheral wall of the holder to position the holder relative to the rotatable shaft in a circumferential direction. An annular magnet is fixed to the holder and surrounds the rotatable shaft. The annular magnet has two magnetic poles of different polarities, which are magnetized in a magnetization direction that coincides with a radial direction of the annular magnet. The positioner is displaced around a rotational axis of the rotatable shaft from the magnetization direction of the annular magnet by about 90 degrees in the circumferential direction.