National Institute of Polar Research （NIPR） has been conducting absolute gravity measurements not only at Japanese Antarctic research station, Syowa since early 1990s, but also other foreign research stations in Antarctica recently. To validate the absolute gravimeter employed, test measurements were conducted at the gravity point located at the machine shop in NIPR usually before and after the measurements in Antarctica. The observed gravity values at the point, however, often varied exceed the expected instrumental errors. To explain the causes of the large gravity variations, we compared the observed gravity values with the precipitations at three AMeDAS（Automated Meteorological Data Acquisition System）stations, groundwater levels at a Tokyo Metropolitan Government observatory, and the height data at four GEONET （GNSS Earth Observation Network System）stations. The result of the comparisons showed that 1） the seasonal or shorter gravity variations were mainly caused by the precipitations and the resultant soil moisture and/or shallow groundwater changes, and 2） the secular or longer period gravity variations were explained by the uplift after the 2011 Tohoku-oki earthquake and the long-term variations of the groundwater level at deeper depths. After removing these effects, the standard deviation of the gravity residuals was less than 3 µGal （1 µGal＝10−8 m/s2）.
