Portable electronic device with electronic compass and method for calibrating compass

A calibrating method for a portable electronic device having azimuth device such as an electronic compass is disclosed. The calibrating method can be achieved by checking at least one sensor in the portable device incorporating the electronic compass configured in the portable device, so as to effectively detect and verify a temporary abnormal magnetic field caused by a stylus movement. When the electronic compass detects an abnormal magnetic field, the operation status of the sensor is checked for any change existence. If the operation status of the sensors changes, the abnormal magnetic field is verified as a temporary magnetic filed due to the movement of the stylus, in which case the electronic compass passes the calibration and goes on detecting the geomagnetic field according to its default setting value.