The reliability of particle size measurement by the sedimentation balance method has been examined by numerical experiment and simulation. In order to shorten the measurement time for sub-micron particles, the effect of electrical-potential applied in a sedimentation bath on particle size measurement is examined. The reliability is evaluated by comparing the true original distribution and estimated results. The reliability of the converged solution by the Twomey iteration method increases as the iteration number increases. Reliability of the converged solution is confirmed to nearly mono-dispersed particles. The original size distribution that follows a log-normal distribution with a geometric standard deviation of 1.1 is estimated with the iteration number of 3000. The reliability of the picket-fence size distribution composed of three kinds of nearly mono-dispersed particles is also confirmed. In order to measure sub-micron particle size distribution, it is effective to apply electrical-potential in the particle sedimentation bath. The simulation result by use of both electrical-potential and gravity provides a better estimated results compared to that of only the gravitational sedimentation method. (C) 2017 Elsevier B.V. All rights reserved.