Toner Display is based on an electrical movement of charged toner particles. Two types of black and white particle charged in the different electric polarity are enclosed in the air space between two transparent electrodes. The black toners are collected to the electrode by an electrostatic force across the insulting layer to display a black image. Those toners can be put to the counter electrode by applying a reverse electric field, and white solid image is displayed.The display contrast and driving voltage depend on the electrical charge of toner particle in the display cell. In this study, the triboelectric charges of particles in the display cell were measured using Q/M meter. Those charges depend on the mixture ratio of two toners. The triboelectric charging mechanism between small toner particles was discussed.