As a simple way to generate monodisperse aerosol particles, the method based on atomization or nebulization of a liquid suspension containing monodisperse polystyrene latex (PSL) particles of known size has often been used. In this study, a nebulizer is developed for stable generation of monodisperse particles, and the following results are obtained : 1) The size distribution of nebulized droplets is determined. 2) The particles formed by the residue after evaporation (RAE) of droplets have been evaluated. 3) An impactor is found effective to reduce RAE particles. 4) The optimum particle number concentrations of liquid suspensions are found in order to avoid the formation of doublet aerosol particles and, atthe same time, to minimize the effect of RAE aerosol particles. 5) The charge distribution of PSL particles are observed. 6) Long term operation is found to be possible. The nebulizer developed in this study is precisely machined within a certain torelance so that anyone can make identical ones which assure the same performance described here.