Geomagnetic sensor having a dip angle detection function and dip angle detection method therefor

A geomagnetic sensor supporting a dip angle detection function. The geomagnetic sensor includes a rotation angle measurement part for measuring pitch and roll angles of the main body with respect to the surface of the Earth; a geomagnetic measurement module for outputting an electric signal corresponding to the geomagnetic field; a memory for storing predetermined reference azimuths and output values of the geomagnetic measurement module corresponding to changes of the pitch and roll angles; and a controller for calculating azimuths by use of the output values of the geomagnetic measurement module, the pitch and roll angles, and predetermined dip angles. The controller establishes at least two dip angles, calculates the azimuth for each dip angle, compares the azimuth to the reference azimuth, and determines a dip angle at the azimuth having a smaller azimuth error as a current dip angle. The geomagnetic sensor can measure a precise dip angle using a simple method.