An empirical water balance model was proposed to correct hydrological disturbances in relative gravity data measured repeatedly at Sakurajima Volcano, southern Kyushu, Japan. Gravity measurements have been conducted at Sakurajima Volcano to quantitatively monitor gravity signals due to magmatic activities, while the signals have often been obscured by the hydrological disturbances originating from precipitation, soil water infiltration, and groundwater flow. We here present the first applied results of the empirical model, in order to evaluate the reproducibility of the estimated hydrological disturbances. The hydrological disturbances were simply calculated by the product of the land water storage and the instantaneous gravity response to precipitation of 1 mm depth, which were estimated using the observed meteorological data and the digital elevation model, respectively. The calculated hydrological disturbance was consistent with the observed absolute gravity data at Harutayama Station from 2010 to 2011 within 8 µgal （1 µgal = 1×10^－8 m/s² ）, which was smaller than the typical accuracy of relative gravity measurements （～10 µgal）. In addition, after we subtracted (i.e., corrected) the calculated disturbances from the measured relative gravity data at Sakurajima Volcano, the average amplitude of the corrected gravity changes during 2007-2009 was reduced by 90% compared with that of the original gravity data. Since gravity changes have been measured using both absolute and relative gravimeters at volcanic areas these days, hydrological disturbance corrections should be applied to the relative gravity data, not only to the absolute one. By sophisticating the effects of spatiotemporal variations in precipitation, evapotranspiration, and infiltration capacity, this model will enable us to robustly monitor long-period and wide-spread gravity variations associated with volcanic activities.