To design composite materials, and to optimize the manufacturing condition, quantitative evaluation of the dispersion state of filler contained in composite materials is important. In this study, the batch kneading of thermosetting resin and circular particles and the continuous kneading of thermoplastics resin and electric conductive fibers were performed, and the desperson state in these composite materials was evaluated with fractal dimension and coordination number. According to the evaluation, the fillers were dispersed in a uniform state if the value of fractal dimension was high, and the aggregation of the fillers was broken substantially if the coordination number had a lower value. Based on the relation between fractal dimension and the state of flow in the kneader as well as that between coordination number and the state of flow, the kneading mechanism was discussed. It became clear that the aggregation of the fillers was broken preferentially if elastic mixing was performed, and the diffusion of the fillers in the material was accelerated if counter-flow or diffusional mixing was pre-dominant. It was also pointed out that an excellent electric conductive resin could be obtained when the product of the fractal dimension and coordination number was a high value.