The particle size distribution of cylinder-shaped solid particles was measured using a buoyancy weighing-bar method where the liquid phase density was adjusted to settle or float the particles. The particle size distribution obtained in our experiment agrees with the particle size measured by other method. The present study demonstrates that a buoyancy weighing-bar method, a novel method for measuring the particle size distribution, is suitable for measuring the particle size distribution of a floating solid. The precision of the resulting particle size distribution is comparable to that of a laser diffraction/scattering method as well as a direct measurement with a micrometer. Moreover, this buoyancy weighing-bar method can measure the particle size distribution even in a mixture of two particles with different sizes. (C) 2010 Elsevier B.V. All rights reserved.