Pulverization devices of toner were studied experimentally as well as numerically in the point of view of fluid dynamics. Supersonic flow, into which raw toner powder is poured through an injector, is injected against a flat plate or a coneshape obstacle. After passing through a shock wave formed in front of the obstacle, the raw toner powder is produced.Based on the flow visualization study together with numerical analysis of the flow field, the velocity field and the pressure and the density distributions are determined. As the results, the optimum shape of the obstacle and the flow conditions are found.