Modification of a core particle surface was achieved by using fine particles and by a high-speed impact method that is useful for the production of composite particles. Two kinds of silica particles differing in size and physical properties were tested for deposition onto polyimide cores. The effects of different composite-particle-forming conditions on the structure and physical properties were evaluated with scanning electron microscopy, the Brunauer-Emmett-Teller method, energy dispersive X-ray analysis and an ultra-micro hardness tester. These evaluations confirmed that silica particles existed on the polyimide core surface, and enhanced ability of the core pressure. Ultrasonic irradiation was used to examine the adhesion of silica to polyamide and the dynamic stability of the composite particles. It was observed that both static stability, as measured by the hardness tester, and the dynamic stability of the composite particles when ultrasonicated varied depending on the combination of particles used and the process by which the core particles and the fine particle were combined.