Quantitative evaluation of the composite particle layer formed with a high speed elliptical-rotor type mixer and the state of the composite layer are examined. Hematite particles having a median diameter of 0.48 mu m were composed on the surface of glass beads having a median diameter of 107 mu m. The quantity of adhesion of hematite particles was measured by ICP emission spectroscopy and the influence of operation condition of the mixer is elusidated. The state of composite particle layer was characterized by the luminosity measurement of the composite particle surface using an optical sensor. It is found that the amount of adhesion of fine hematite particles increases with composing, however the luminosity of composite particles attains an equilibrium state. Namely, the luminosity equilibrium of the composite particles implies that the surface of the core particles is uniformly covered by hematite. The optical measurement of the composite particles is effective to characterize the composite particle layer on the core particles. A particle composing process with a high-speed elliptical-rotor-type mixer is described as the following two processes: The first is the formation process of the coating layer by collision of hematite particles and the second is the growth process of the composite particle layer. The increment of adhered particles on the core particles is described by cumulative shearing energy subjected to the composite particles. The process with the high-speed elliptical-rotor-type mixer is the same as the composing by high shear stress.