hanges in the daily variation of H component due to magnetic storms with a duration of hours to days is the space weather information is very important for further decision making for the user. Activity disturbance caused wave/influx of energetic particles that arise through the solar wind, can solve the earth's magnetic field is strong at very short intervals. Changes in the daily variation H component is generally an increase or decrease up to hundreds of nano tesla from a stable ondition. In the paper be discussion analysis of changes in the daily variation of H component magnet during magnetic storms using double Fourier series. In order to obtain information from changes daily variation of H component during magnetic storms through data from monitoring stations geomagnetic Biak and Tangerang. The results of analysis obtained 3 times a magnetic storm events occur fluctuation SSG to daily variations in H component in Tangerang April 2001, in order 171nT,-and-125nT 221nT. Magnetic storm SSC 28 April 2001 showed changes occur daily variation of H component in the station at Biak -467nT and 1124nT.