The effect of rotor shape on the composite process of fine particles which covers the surface of the core particles is investigated by using a high-speed elliptical-rotor-type mixer. Two kinds of different shape of rotors are used for experiments. As a result, the composite process strongly depends on the rotor shape, and it is explained by the average contact force acting between the core particles and the rotor wall which is calculated by a 3-dimensional numerical simulation (PEM) already proposed by the authors.