Relative gravity values were repeatedly measured at 19 gravity points in and around Sakurajima Volcano in October 2021 and March 2022, to monitor spatiotemporal mass variations associated with volcanic activity. The gravity values obtained from 1998 to 2022 showed a clear increase of up to +4.3 Gal/yr in the central part of the volcano. The gravity increase can be explained by the point mass increase of 8 × 109 kg/yr under the center of the volcano at a depth of 3 km below sea level. This result implies that volcanic mass continuously increases under Sakurajima Volcano, even during the quiet period of eruptive activities at the Minami-dake crater.