Provided that the resistance for non-magnetic fields is "1", the resistance will change approx. four times when a magnetic flux density of 0.3T is applied. In the range where the magnetic flux density is 0.08T or less, the ratio of resistance change will be decreased. The sensors provide a bias magnetic field so that the sensors operate in the range where the ratio of resistance change relative to magnetic flux density is high. For details, refer to the section titled "Characteristics of Magnetoresistive Elements".