In general, the larvae of Protaetia brevitarsis is raised on fermented oakwood sawdust. Many attempts have been to changes components sawdust, such as using other tree instead of oakwood or adding another material. Like this some study exists, about 'component' of sawdust, however little is known of relation between larval growth and quality of sawdust. The phenomenon-big particle size sawdust flows up on excrement from the larvae-is occurring in used sawdust for raising the larvae. This study was conducted to observe the larvae and adult of Protaetia brevitarsis act according to each sawdust particle size. We conducted choice experiments with Protaetia brevitarsis, which were offered sawdust differing in particle size. Females preferred to lay their eggs on the fine particle sawdust. Also in the case of larvae, the more fine sawdust particle has the more high level of preference, and so is hatchability. Especially larvae tend to be slanted toward finer sawdust. Growth rate of the larvae was shown the highest level in the finest sawdust just as others do. These results show that fine sawdust particle size is advantage for larval development and oviposition.