MAGNETIC FIELD DETECTING APPARATUS AND ELECTRONIC COMPASS USING THE SAME

[Object] To provide a magnetic sensing device that can obtain the strength of an external magnetic field under circumstances where a relatively strong disturbance takes place, and an electronic compass using the same. [Solving Means] A current c supplied to a coil 112 and its current deviation x are set. The current c, current c+x, and current cx are supplied to the coil 112 to generate AC magnetic fields, which are then applied to MR elements 111, and voltages V 0 to V 2 are detected. Using the voltages V 0 to V 2 detected by the voltage detector 13, an amplitude determining unit 14 determines whether the magnetic field is outside a sensing range of the MR elements 111. When the magnetic field is outside the sensing range of the MR elements 111, an amplitude controller 17 increases the current deviation x, and the current amplifier 18 supplies current using the current deviation newly set by the amplitude controller 17 to the coil 112. In this manner, the slope of the MR elements 111 is detected.