An input device using a geomagnetic sensor includes a geomagnetic sensor outputting a voltage corresponding to geomagnetism, and a control part calculating an azimuth using the voltage output from the geomagnetic sensor and calculating the rotation angle by comparing the azimuth to a previously measured azimuth, thereby generating the input signal corresponding to the rotation angle when the input device is tilted within a certain range. Accordingly, unwanted generation of the input signal is prevented when the input device is tilted by more than a certain angle.