Three-dimensional variations of the plasma bulk flow direction in the plasma sheet at XGSE~-60Re were observed by the Low Energy Particle (LEP) instrument on board the GEOTAIL satellite. These variations have two components, namely a rapidly varying component of which the period is about 8 minutes and a more slowly varying component. Separating these two components, we have found a period when the rapidly varying component showed clear rotations while the direction of the slowly varying component nearly corresponded with the direction of the magnetic field. We have calculated the rotation axis of the rapidly varying component during this period and have found that the direction of the rotation axis changed by nearly 90¿ in a step-like motion while the vortex motion remained coherent in the plane perpendicular to the moving rotation axis. We discuss several possible mechanisms for these variations, MHD waves, vortex structures, and tail flapping motion with velocity shears.