A geomagnetic sensor and method are provided. The geomagnetic sensor has a geomagnetic detection module for outputting an electric signal value corresponding to a geomagnetism, a tilt detection module for detecting a tilt angle with reference to a reference plane, a memory for storing a constant for each azimuth angle, and a central processing unit for performing a first azimuth computation using an initial value of the constants, the electric signal value and the tilt angle, and for performing a second azimuth computation by detecting from the memory a constant corresponding to the resultant azimuth of the first azimuth computation and using the detected constant. The method includes outputting an electric signal corresponding to a geomagnetism; normalizing the output electric signal; detecting a tilt angle with respect to a reference plane; performing a first azimuth computation; detecting a constant corresponding to the resultant azimuth; and performing a second azimuth computation.