The purpose of this study was to examine the relationship between the buoyancy of synchronized swimmers and the airborne weight of basic positions. Whole-body volume, buoyancy, underwater weight, and airborne weight at 12 levels in basic positions were measured for eight female synchronized swimmers (15.6 ± 2.98 years, 1.60 ± 0.05 m, 52.7 ± 4.40 kg). The main results were as follows. The surplus buoyancy of synchronized swimmers was 2.19 ± 1.78 kgf. In the upright position, the airborne weight of double arm changed from 8.58 ± 0.63 kgf (16.3%) at the shoulders to 28.44 ± 2.99 kgf (53.9%) at the mid-pelvis. In the inverted position, the airborne weight of double leg changed from 3.77 ± 0.97 kgf (7.1%) at the kneecap to 7.77 ± 0.95 kgf (14.7%) at the clotch level. In the horizontal position, the airborne weight for the ballet leg double changed from 7.18 ± 0.94 kgf (13.6%) at the mid-thigh to 12.95 ± 1.72 kgf (24.6%) at the crotch level. Although there was no effect from greater surplus buoyancy on positions with a large airborne weight, swimmers with greater buoyancy could more efficiently hold parts of the body above the water in positions with a small airborne weight. It is important to increase supporting force via propulsive techniques to support large airborne weights.