An electrostatic precipitator (ESP) is a particle control device that uses electrostatic forces to move the particles out of the flowing gas stream and onto collector electrodes. The particles are given an electrical charge by forcing them to pass through a corona discharge field, a region in which gaseous ions flow. The electrical field that forces the charged particles to the walls comes from electrodes maintained at high voltage in the center of the flow lane. Dielectric constant of materials on particle charging is important factors influencing collection efficiency of the ESP. In this study, we analytically investigated the dependence of unipolar charging of particles on the dielectric constant of the particle material. The examined particles (10 nm – 10 μm) cover a wide range of dielectric constant but have almost the spherical morphology. Prediction of mean charge per particle show very small differences among different materials. The level of the small difference is consistent with the estimation by White’ equation (1963).