[Abstract] In order to measure the particle-particle interactions of the toner particle in high accuracy,the changes in force to act between the toner particle on the top of the tip and the one into the compressed layer of toner powder were measured by colloid probe atomic force microscopy. The additives that consisted of SiO2 were adhered on the surface of the toner particle and the influence of the surface coverage of SiO2 on the particle-particle interactions was examined. As the result, the particle-particle interactions decreased in inverse proportion at the surface coverage of SiO2 in the condition of 26% or less. Next, the relationships between the particle-particle interactions and the flow properties were examined by using conical rotor method. When the mean particle diameter was same, there was the first strong positive correlation between the particle-particle interaction and the shearing torque that passed the starting point.