An analytical ultracentrifuge was used to characterize the behaviors of ultracentrifugal sedimentation of bovine serum albumin solutions. We obtained data both for the sedimentation velocity and for the growth rate of the sediment that accumulates during ultracentrifugation. Effects of the rotor speed, the solution concentration, and the volume of the solution contained in the cell on the sedimentation behaviors were investigated experimentally. The sedimentation behaviors and the properties of the compressible sediment were explained well in terms of the theory which has been applied with respect to particulate suspension. Finally, it was shown that such factors of the solution environment as the solution pH and the salt concentration have a large effect on the sedimentation behaviors.