Patent ID: 7268544

Claim:
A magnetism detecting device comprising: a magnetometric sensor that detects magnetism and outputs an output voltage based on the detected magnetism; a bias magnetic field generating unit that applies positive and negative bias magnetic fields to the magnetometric sensor; a voltage applying unit that applies a positive voltage and a negative voltage to the magnetometric sensor; a detecting unit that detects voltage values obtained based on the output voltage; and an operating unit that calculates an azimuth using the voltage values, wherein the detecting unit calculates a first output corresponding to a difference between two voltage values each corresponding to the positive and negative bias magnetic fields, and the positive voltage, wherein the detecting unit calculates a second output corresponding to a difference between two voltage values each corresponding to the positive and negative bias magnetic fields, and the negative voltage, and wherein the detecting unit eliminates an offset voltage included in the first output and the second output by taking difference between the first output and the second output.