Apparatus and method for calibrating offset of geomagnetic sensor

An apparatus and a method for calibrating offset of a geomagnetic sensor are provided to perform automatic calibration of the sensor in the direction of each axis promptly when the offset values are modified by ambient magnetic field environment, by utilizing values detected from the geomagnetic sensor. An offset calibrating apparatus(10) for a geomagnetic sensor comprises a sensor(11), a data acquiring unit(12), a data storage unit(13), an offset calculation judgment unit(14), an offset calculation unit(15), and a filtering unit(16). The geomagnetic sensor includes a plurality of axial directions forming 90° with each other. The data acquiring unit normalizes each value about each axial direction detected from the geomagnetic sensor, and compares the distance between the normalized value and the most recently detected value with a predetermined first critical value. The data storage unit stores the value which is greater than the first critical value. The offset calculation judgment unit calculates standard deviation of the values stored in the data storage unit, and compares the obtained standard deviation with a predetermined second critical value. If the standard deviation is greater than the second critical value, the offset calculation unit computes an offset of value about each axial direction by using the value stored in the data storage unit.