Toner tribocharging characteristics are affected by various factors : charging method, materials, environment and others. The toner charge stability is important for keeping a good image quality. Toner charge distribution is one of important factors in electrophotographic printing process. The toner charge distribution is changed by toner mixing conditions of toner weight % and toner mixing time. In this study, aerodynamic size and electrostatic charge distribution of the toner particles are measured individually by E-SPART (Electrical Single Particle Aerodynamic Relaxation Time) analyzer. It is found that two peaks in toner charge histogram arise in some conditions.